Hundreds of albums named " 's Acidfree album "

i have 2 users in my weblog. and when i upgraded my Drupal from 4.7.5 to 5.1, and upgraded to Acidfree 5.x-1.x-dev,

i got hundreds of albums named like this. then i deleted the nodes manually from the db. so i gotta ask, where are these albums coming from? why am i getting hundreds of (nearly a thousand) garbage nodes?