Index: /trunk/src/org/openstreetmap/josm/data/imagery/WMTSTileSource.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/imagery/WMTSTileSource.java	(revision 11789)
+++ /trunk/src/org/openstreetmap/josm/data/imagery/WMTSTileSource.java	(revision 11790)
@@ -25,4 +25,5 @@
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Predicate;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -578,4 +579,9 @@
                 proj.toCode());
 
+        if (candidates.size() > 1 && defaultLayer != null) {
+            candidates = candidates.stream()
+                    .filter(t -> t.tileMatrixSet.identifier.equals(defaultLayer.getTileMatrixSet()))
+                    .collect(Collectors.toList());
+        }
         if (candidates.size() == 1) {
             Layer newLayer = candidates.iterator().next();