diff --git a/cck.install b/cck.install
index 49a2f9b..75526ed 100644
--- a/cck.install
+++ b/cck.install
@@ -93,3 +93,61 @@ function cck_update_7000() {
     db_add_field('cck_field_settings', 'language', $field);
   }
 }
+
+function cck_update_7001(&$sandbox = array()) {
+  $ret = array();
+
+  // Query the existing D6 files table for possible duplicate URIs in D7.
+  if (db_table_exists('files')) {
+    try {
+      db_add_index('files', 'path', array('filepath'));
+    }
+    catch(DatabaseSchemaObjectExistsException $e) {}
+    if (!isset($sandbox['progress'])) {
+      $sandbox['progress'] = 0;
+      $sandbox['current_file'] = 0;
+      $sandbox['max'] = db_query("SELECT COUNT(f1.fid) FROM {files} f1 WHERE (SELECT COUNT(f2.filepath) FROM {files} f2 WHERE f2.filepath = f1.filepath && f1.`fid` > f2.`fid` LIMIT 1) > 0")->fetchField();
+    }
+    // Log an error if the destination does not contain a valid stream.
+    $destination = variable_get('file_default_scheme', 'public') . '://';
+    $destination_scheme = file_uri_scheme($destination);
+    if (!$destination_scheme || !file_stream_wrapper_valid_scheme($destination_scheme)) {
+      watchdog('cck', 'The file could not be copied, because the destination %destination is invalid.', array('%destination' => $destination), WATCHDOG_ERROR);
+      throw new Exception('error');
+    }
+
+    // Update 50 files at a time.
+    $result = db_query("SELECT f1.fid, f1.filename, f1.filepath FROM {files} f1 WHERE (SELECT COUNT(f2.filepath) FROM {files} f2 WHERE f2.filepath = f1.filepath && f1.`fid` > f2.`fid` LIMIT 1) > 0 AND f1.fid > :fid ORDER BY f1.fid LIMIT 50",
+      array(':fid' => $sandbox['current_file']));
+
+    foreach ($result as $record) {
+      // Duplicate file via copy.
+      if (file_exists($record->filepath)) {
+        $new_path = str_replace("public://", "", file_destination($destination . $record->filepath, FILE_EXISTS_RENAME));
+        $saved_filepath = file_unmanaged_copy($record->filepath, $new_path, FILE_EXISTS_RENAME);
+      }
+      else {
+        $saved_filepath = $record->filepath . "_DUMMY_COPY_" . $record->fid;
+      }
+
+      // Update the database to use the new filename.
+      if ($saved_filepath) {
+        $saved_filepath_base = basename($saved_filepath);
+        $num_updated = db_update('files')
+          ->fields(array(
+            'filename' => $saved_filepath_base,
+            'filepath' => $saved_filepath,
+          ))
+          ->condition('fid', $record->fid, '=')
+          ->execute();
+         watchdog('cck', "Updated file: fid: $record->fid, $record->filename to $saved_filepath_base");
+      }
+      $sandbox['current_file'] = $record->fid;
+      $sandbox['progress']++;
+    }
+
+    $sandbox['#finished'] = empty($sandbox['max']) ? 1 : ($sandbox['progress'] / $sandbox['max']);
+  }
+
+  return $ret;
+}