diff --git a/assets/js/map.ts b/assets/js/map.ts
index d96c9c4..09d2593 100644
--- a/assets/js/map.ts
+++ b/assets/js/map.ts
@@ -1748,6 +1748,46 @@ let MapAPRSMap = {
     // Remove existing marker if it exists (without affecting trails since we're just replacing it)
     self.removeMarkerWithoutTrail(data.id);
 
+    // When adding a "most recent" marker, convert any existing "current" markers
+    // for the same callsign_group to historical dots. This prevents duplicate labels
+    // when multiple senders report the same object (e.g. two stations tracking one radiosonde).
+    if (data.is_most_recent_for_callsign && self.callsignIndex) {
+      const csGroup = data.callsign_group || data.callsign;
+      if (csGroup) {
+        const existingIds = self.callsignIndex.get(csGroup);
+        if (existingIds) {
+          for (const eid of existingIds) {
+            if (String(eid) === String(data.id)) continue;
+            const eState = self.markerStates.get(eid);
+            const eMarker = self.markers.get(eid);
+            if (
+              eState &&
+              eMarker &&
+              eState.is_most_recent_for_callsign
+            ) {
+              eState.historical = true;
+              eState.is_most_recent_for_callsign = false;
+              eMarker.setIcon(
+                self.createMarkerIcon({
+                  id: String(eid),
+                  lat: eState.lat,
+                  lng: eState.lng,
+                  callsign: eState.callsign || csGroup,
+                  callsign_group: eState.callsign_group || csGroup,
+                  symbol_table_id: eState.symbol_table,
+                  symbol_code: eState.symbol_code,
+                  historical: true,
+                  is_most_recent_for_callsign: false,
+                  popup: eState.popup,
+                }),
+              );
+              (eMarker as APRSMarker)._isHistorical = true;
+            }
+          }
+        }
+      }
+    }
+
     // Create marker - use simple dot for older historical positions, APRS icon for most recent
     const marker = L.marker([lat, lng], {
       icon: self.createMarkerIcon(data),
diff --git a/lib/aprsme_web/live/map_live/data_builder.ex b/lib/aprsme_web/live/map_live/data_builder.ex
index 2ed2d1c..4458a67 100644
--- a/lib/aprsme_web/live/map_live/data_builder.ex
+++ b/lib/aprsme_web/live/map_live/data_builder.ex
@@ -49,6 +49,7 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
         build_packet_data(packet, is_most_recent, locale)
       end)
       |> Enum.filter(& &1)
+      |> deduplicate_by_callsign_group()
 
     Process.delete(:weather_callsigns_cache)
     result
@@ -111,6 +112,7 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
       symbol_code = get_packet_field(packet, :symbol_code, ">")
 
       callsign = display_name(packet)
+      label = map_label(packet)
 
       # For historical (non-most-recent) packets, use a simple red dot HTML
       # instead of the full APRS symbol — matches what the JS createMarkerIcon
@@ -120,19 +122,16 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
           AprsmeWeb.SymbolRenderer.render_marker_symbol(
             symbol_table_id,
             symbol_code,
-            callsign,
+            label,
             32
           )
         else
-          historical_dot_html(callsign)
+          historical_dot_html(label)
         end
 
       raw_comment = get_packet_field(packet, :comment, "")
       clean_comment = Aprsme.EncodingUtils.sanitize_comment(raw_comment)
 
-      # Use map_label for display, but keep display_name for grouping
-      label = map_label(packet)
-
       %{
         "id" => if(is_most_recent, do: "current_#{get_packet_id(packet)}", else: "hist_#{get_packet_id(packet)}"),
         "lat" => to_float(lat),
@@ -229,7 +228,7 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
   @spec build_simple_popup(map(), boolean()) :: String.t()
   def build_simple_popup(packet, has_weather) do
     # Build popup HTML directly without database queries
-    callsign = display_name(packet)
+    callsign = map_label(packet)
     timestamp_dt = get_packet_received_at(packet)
     cache_buster = System.system_time(:millisecond)
 
@@ -685,4 +684,15 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
     |> Enum.map(fn packet -> build_minimal_packet_data(packet, false, has_weather) end)
     |> Enum.filter(& &1)
   end
+
+  # When multiple senders track the same object, keep only one "current" marker
+  # per callsign_group to avoid duplicate labels on the map.
+  defp deduplicate_by_callsign_group(marker_list) do
+    marker_list
+    |> Enum.reduce(%{}, fn marker, acc ->
+      group = marker["callsign_group"] || marker["callsign"]
+      Map.put(acc, group, marker)
+    end)
+    |> Map.values()
+  end
 end
diff --git a/lib/aprsme_web/live/map_live/index.ex b/lib/aprsme_web/live/map_live/index.ex
index 2ae91ac..49e6be2 100644
--- a/lib/aprsme_web/live/map_live/index.ex
+++ b/lib/aprsme_web/live/map_live/index.ex
@@ -849,51 +849,13 @@ defmodule AprsmeWeb.MapLive.Index do
   end
 
   def handle_info({:packet_batch, packets}, socket) do
-    # Process batch: collect marker data and removal IDs without pushing events
-    {socket, marker_data_list, removal_ids} =
-      Enum.reduce(packets, {socket, [], []}, fn packet, {acc_socket, markers, removals} ->
-        {new_socket, marker_data, removed_id} = process_packet_for_batch(packet, acc_socket)
-        markers = if marker_data, do: [marker_data | markers], else: markers
-        removals = if removed_id, do: [removed_id | removals], else: removals
-        {new_socket, markers, removals}
-      end)
+    {socket, marker_data_list, removal_ids} = process_packet_batch(packets, socket)
 
-    # Push a single batched remove event for all removals
     socket =
-      if removal_ids == [] do
-        socket
-      else
-        DisplayManager.remove_markers_batch(socket, removal_ids)
-      end
-
-    socket = assign(socket, :last_update_at, DateTime.utc_now())
-
-    # Send heat map update once if in heat map mode, otherwise batch markers
-    socket =
-      cond do
-        socket.assigns.map_zoom <= 8 and marker_data_list != [] ->
-          DisplayManager.send_heat_map_for_current_bounds(socket)
-
-        marker_data_list != [] ->
-          reversed = Enum.reverse(marker_data_list)
-
-          # Extract convert_to_historical callsign keys from markers that replaced existing ones
-          convert_to_historical =
-            reversed
-            |> Enum.map(&Map.get(&1, "convert_from"))
-            |> Enum.filter(& &1)
-            |> Enum.uniq()
-
-          markers = prepare_markers_for_push(reversed, socket.assigns.station_popup_open)
-
-          push_event(socket, "new_packets", %{
-            packets: markers,
-            convert_to_historical: convert_to_historical
-          })
-
-        true ->
-          socket
-      end
+      socket
+      |> remove_markers_if_needed(removal_ids)
+      |> assign(:last_update_at, DateTime.utc_now())
+      |> update_display_for_batch(marker_data_list)
 
     {:noreply, socket}
   end
@@ -1100,6 +1062,61 @@ defmodule AprsmeWeb.MapLive.Index do
     end
   end
 
+  defp process_packet_batch(packets, socket) do
+    Enum.reduce(packets, {socket, [], []}, fn packet, {acc_socket, markers, removals} ->
+      {new_socket, marker_data, removed_id} = process_packet_for_batch(packet, acc_socket)
+      markers = if marker_data, do: [marker_data | markers], else: markers
+      removals = if removed_id, do: [removed_id | removals], else: removals
+      {new_socket, markers, removals}
+    end)
+  end
+
+  defp remove_markers_if_needed(socket, []), do: socket
+
+  defp remove_markers_if_needed(socket, removal_ids) do
+    DisplayManager.remove_markers_batch(socket, removal_ids)
+  end
+
+  defp update_display_for_batch(socket, []), do: socket
+
+  defp update_display_for_batch(socket, marker_data_list) do
+    if socket.assigns.map_zoom <= 8 do
+      DisplayManager.send_heat_map_for_current_bounds(socket)
+    else
+      send_marker_batch(socket, marker_data_list)
+    end
+  end
+
+  defp send_marker_batch(socket, marker_data_list) do
+    reversed = Enum.reverse(marker_data_list)
+
+    # Deduplicate by callsign_group — when multiple senders track the same
+    # object (e.g. two stations reporting the same radiosonde), keep only
+    # the most recent packet per group to avoid duplicate "current" markers.
+    deduped =
+      reversed
+      |> Enum.reduce(%{}, fn marker, acc ->
+        group = marker["callsign_group"] || marker["callsign"]
+        Map.put(acc, group, marker)
+      end)
+      |> Map.values()
+
+    # Send callsign_groups so the frontend can look up existing markers
+    # via its callsignIndex (keyed by callsign_group, not by packet UUID)
+    convert_to_historical =
+      deduped
+      |> Enum.map(fn m -> m["callsign_group"] || m["callsign"] end)
+      |> Enum.filter(& &1)
+      |> Enum.uniq()
+
+    markers = prepare_markers_for_push(deduped, socket.assigns.station_popup_open)
+
+    push_event(socket, "new_packets", %{
+      packets: markers,
+      convert_to_historical: convert_to_historical
+    })
+  end
+
   # Handle replaying the next historical packet
 
   @impl true
diff --git a/test/aprsme_web/live/map_live/data_builder_test.exs b/test/aprsme_web/live/map_live/data_builder_test.exs
index c79d81b..375a0ae 100644
--- a/test/aprsme_web/live/map_live/data_builder_test.exs
+++ b/test/aprsme_web/live/map_live/data_builder_test.exs
@@ -143,6 +143,9 @@ defmodule AprsmeWeb.MapLive.DataBuilderTest do
       assert result["callsign"] == "DB0SDA"
       # But grouping uses object name
       assert result["callsign_group"] == "P-K5SGD"
+      # Symbol HTML should show sender, not object name
+      assert result["symbol_html"] =~ "DB0SDA"
+      refute result["symbol_html"] =~ "P-K5SGD"
     end
 
     test "build_minimal_packet_data uses red dot HTML for historical (non-most-recent) packets" do
@@ -343,5 +346,31 @@ defmodule AprsmeWeb.MapLive.DataBuilderTest do
       groups = Enum.map(results, & &1["callsign_group"])
       assert Enum.all?(groups, &(&1 == "P-K5SGD"))
     end
+
+    test "build_simple_popup shows sender for object packets" do
+      packet = %{
+        id: Ecto.UUID.generate(),
+        sender: "WA0YMH-2",
+        base_callsign: "WA0YMH",
+        ssid: "2",
+        object_name: "X3234025",
+        is_object: true,
+        is_item: false,
+        lat: 33.251833,
+        lon: -95.719833,
+        data_type: "object",
+        received_at: DateTime.utc_now(),
+        symbol_table_id: "/",
+        symbol_code: "O",
+        comment: "Clb=5.9m/s t=-58.5C 404.800MHz Type=RS41-NG rdzTTGOsonde",
+        has_position: true,
+        path: "TCPIP*,qAR,WA0YMH-2"
+      }
+
+      popup = DataBuilder.build_simple_popup(packet, false)
+
+      assert popup =~ "WA0YMH-2"
+      refute popup =~ "X3234025"
+    end
   end
 end