Comments created_by changed from Guest to Admin

hi i dort know if i have done something wrong, but i found a lot of user_id 0 entrys in discuss_users_history Table and deleted all those with User Id 0 because they blowing my Database with guest activities.

but i believe, that at the same time something changed in my EB Tables:

All Guest Comments with value created_by 0 in EB easyblog_comment changed now from 0 to 62

is this a Bug? i fixed this with dB Replacer but this is very strange..