diff --git a/base/py/results.py b/base/py/results.py
index 659c0562..464717e5 100644
--- a/base/py/results.py
+++ b/base/py/results.py
@@ -61,6 +61,9 @@ class Results(Markable):
     def __get_dupe_list(self):
         if self.__dupes is None:
             self.__dupes = flatten(group.dupes for group in self.groups)
+            if None in self.__dupes:
+                # This is debug logging to try to figure out #44
+                logging.warning("There is a None value in the Results' dupe list. dupes: %r groups: %r", self.__dupes, self.groups)
             if self.__filtered_dupes:
                 self.__dupes = [dupe for dupe in self.__dupes if dupe in self.__filtered_dupes]
             sd = self.__dupes_sort_descriptor