Index: /trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 8955)
+++ /trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 8956)
@@ -30,4 +30,5 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.regex.Pattern;
 
 import javax.swing.AbstractAction;
@@ -745,5 +746,6 @@
             final GpxData data = toGpxData();
             final GpxLayer gpxLayer = new GpxLayer(data, tr("Converted from: {0}", getName()));
-            gpxLayer.setAssociatedFile(new File(getAssociatedFile().getParentFile(), getAssociatedFile().getName() + ".gpx"));
+            final String filename = getAssociatedFile().getName().replaceAll(Pattern.quote(".gpx.osm") + "$", "") + ".gpx";
+            gpxLayer.setAssociatedFile(new File(getAssociatedFile().getParentFile(), filename));
             Main.main.addLayer(gpxLayer);
             if (Main.pref.getBoolean("marker.makeautomarkers", true) && !data.waypoints.isEmpty()) {