Error on Importing Terms

Everytime I run leech, i get the following error:

# user warning: Duplicate entry '3-4' for key 1 query: INSERT INTO term_node (nid, tid) VALUES (4, 3) in /path/to/source/drupal-5.1/includes/database.mysql.inc on line 172.
# user warning: Duplicate entry '7-4' for key 1 query: INSERT INTO term_node (nid, tid) VALUES (4, 7) in /path/to/source/drupal-5.1/includes/database.mysql.inc on line 172.

However, that is only two of them. There are a full screen full of these errors that show up.