Index: compile_rules_graph.py
==================================================================
--- compile_rules_graph.py
+++ compile_rules_graph.py
@@ -265,18 +265,24 @@
 
 
 def checkRegexes (dAllGraph):
     "check validity of regexes"
     print("  checking regexes...")
+    aRegex = set()
     for sGraphName, dGraph in dAllGraph.items():
         for nKey, dVal in dGraph.items():
             if "<re_value>" in dVal:
                 for sRegex in dVal["<re_value>"]:
-                    _checkRegex(sRegex)
+                    if sRegex not in aRegex:
+                        _checkRegex(sRegex)
+                        aRegex.add(sRegex)
             if "<re_morph>" in dVal:
                 for sRegex in dVal["<re_morph>"]:
-                    _checkRegex(sRegex)
+                    if sRegex not in aRegex:
+                        _checkRegex(sRegex)
+                        aRegex.add(sRegex)
+    aRegex.clear()
 
 def _checkRegex (sRegex):
     #print(sRegex)
     if "¬" in sRegex:
         sPattern, sNegPattern = sRegex.split("¬")