add method to audit duplicate XML files

Specifically, we're auditing whether their content differs from each
other or not. If not, we aren't concerned with handling the duplicates
further, but if the content does differ, we need to figure out how

app/services/ams/missing_instantiations_locator.rb

@@ -82,6 +82,32 @@ def create_subsets_from_merged_map(num_processes: 4)
       end
     end
 
+    def audit_duplicate_xml_files
+      results = JSON.parse(File.read(WORKING_DIR.join('i16-combined-results.json')))
+      asset_paths = results.values.flatten.uniq
+      filename_map = {}
+
+      asset_paths.each do |path|
+        path, asset_id = path.split('/')
+        filename = "#{asset_id.sub('cpb-aacip-', '')}.xml"
+
+        filename_map[filename] ||= {}
+        filename_map[filename][:paths] ||= []
+        filename_map[filename][:paths] << path
+      end
+
+      duplicate_files = filename_map.select { |_filename, attrs| attrs[:paths].size > 1 }
+
+      duplicate_files.each do |filename, attrs|
+        file_contents = attrs[:paths].map { |path| File.read(WORKING_DIR.join(path, filename)) }
+        duplicate_files[filename][:content_differs] = file_contents.uniq.size > 1
+      end
+
+      File.open(WORKING_DIR.join('i16-duplicate-xml-files-audit.json'), 'w') do |file|
+        file.puts JSON.pretty_generate(duplicate_files)
+      end
+    end
+
     private
 
     def map_asset_id_to_inst_ids(xml_file)