diff --git a/tests/scripts/audit-validity-dates.py b/tests/scripts/audit-validity-dates.py
index 6c8a4e81fb..127c0a0fe0 100755
--- a/tests/scripts/audit-validity-dates.py
+++ b/tests/scripts/audit-validity-dates.py
@@ -209,13 +209,11 @@ class Auditor:
         X.509 data(DER/PEM format) to an X.509 object.
       - walk_all: Defaultly, it iterates over all the files in the provided
         file name list, calls `parse_file` for each file and stores the results
-        by extending Auditor.audit_data.
+        by extending the `results` passed to the function.
     """
     def __init__(self, logger):
         self.logger = logger
         self.default_files = self.collect_default_files()
-        # A list to store the parsed audit_data.
-        self.audit_data = [] # type: typing.List[AuditData]
         self.parser = X509Parser({
             DataType.CRT: {
                 DataFormat.PEM: x509.load_pem_x509_certificate,
@@ -257,15 +255,27 @@ class Auditor:
                 return audit_data
         return None
 
-    def walk_all(self, file_list: typing.Optional[typing.List[str]] = None):
+    def walk_all(self,
+                 results: typing.Dict[str, AuditData],
+                 file_list: typing.Optional[typing.List[str]] = None) \
+        -> None:
         """
-        Iterate over all the files in the list and get audit data.
+        Iterate over all the files in the list and get audit data. The
+        results will be written to `results` passed to this function.
+
+        :param results: The dictionary used to store the parsed 
+                        AuditData. The keys of this dictionary should
+                        be the identifier of the AuditData.
         """
         if file_list is None:
             file_list = self.default_files
         for filename in file_list:
             data_list = self.parse_file(filename)
-            self.audit_data.extend(data_list)
+            for d in data_list:
+                if d.identifier in results:
+                    results[d.identifier].locations.extend(d.locations)
+                else:
+                    results[d.identifier] = d
 
     @staticmethod
     def find_test_dir():
@@ -485,11 +495,9 @@ def main():
         end_date = start_date
 
     # go through all the files
-    td_auditor.walk_all(data_files)
-    sd_auditor.walk_all(suite_data_files)
-    audit_results = td_auditor.audit_data + sd_auditor.audit_data
-
-    audit_results = merge_auditdata(audit_results)
+    audit_results = {}
+    td_auditor.walk_all(audit_results, data_files)
+    sd_auditor.walk_all(audit_results, suite_data_files)
 
     logger.info("Total: {} objects found!".format(len(audit_results)))
 
@@ -504,7 +512,7 @@ def main():
         filter_func = None
 
     # filter and output the results
-    for d in sorted(filter(filter_func, audit_results), key=sortby_end):
+    for d in sorted(filter(filter_func, audit_results.values()), key=sortby_end):
         list_all(d)
 
     logger.debug("Done!")