Error Duplicate Entry while Step "Installing Projectfork 4" in Migration tool

Migration fails every time at this point (Step 4 in migration process). Any hints?

Duplicate entry '1' for key 'PRIMARY' SQL=INSERT INTO pntj3_pf_repo_dirs (id, asset_id, project_id, title, alias, description, created, created_by, modified, modified_by, checked_out, checked_out_time, attribs, access, protected, parent_id, lft, rgt, level, path) VALUES (1, 0, 0, 'Root', 'root', '', '0000-00-00 00:00:00', 0, '0000-00-00 00:00:00', 0, 0, '0000-00-00 00:00:00', '', 1, 1, 0, 0, 1, 0, '');