Mistake, nopes, Most of them are deliberate and it looks to me that create topic in Meta just to ask below in some different wordings in Meta.

"Hi friends, I copied pasted 100 of posts, now I get banned, I just need to know, which post you find it copied?
I will not use that website/source for copying now onwards in my newly created accounts. Do not worry, I will keep copy pasting from the sources that you have not discovered till now "

I do not know, every plagarist until given proof claim himself/herself innocent and they are caught in multiple posts.