Index: src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java
===================================================================
--- src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java	(revision 225)
+++ src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java	(revision 226)
@@ -250,4 +250,6 @@
 		if (ls1.id == ls2.id && ls1.id != 0)
 			return true;
+		//if (ls1.id != 0 && ls2.id != 0)
+		//	return false;
 		if (ls1.incomplete || ls2.incomplete)
 			return false;
@@ -288,5 +290,5 @@
 		if (other.keys == null)
 			return;
-		if (my.keySet().containsAll(other.keys.entrySet()))
+		if (my.keySet().containsAll(other.keys.keySet()))
 			return;
 		if (my.keys == null)