backend: test for exact DisplayName match

- The ListMaps method is unexpectedly finding DisplayName substrings

pkg/web_api/submissions.go

@@ -567,8 +567,12 @@ func (svc *Service) ActionSubmissionTriggerSubmit(ctx context.Context, params ap
 	if err != nil {
 		return err
 	}
-	if len(maps_list) != 0 {
-		return ErrDisplayNameNotUnique
+
+	// The map search finds substrings, we only want exact matches
+	for _, m := range maps_list {
+		if m.DisplayName == submission.DisplayName {
+			return ErrDisplayNameNotUnique
+		}
 	}
 
 	// transaction