Thanks @cheetah. From my investigation, it looks like @iambamiwa1 and @charlie16 have the same owner and use the same strategy of plagiarizing all of there own posts. These accounts resteem other accounts interspersed with plagiarized posts, which generally are other Steem posts.

After I downvoted all of @charlie16's plagiarized posts, @charlie16 downvoted all of my posts and comments. Then @iambamiwa1 did the same, hence why I think they are owned by the same person. These downvotes don't bother me because these accounts have so little power.

I will now go through @iambamiwa1's post and downvote the plagiarism.

@themarkymark I haven't noticed these accounts using voting bots, but should they be added to your blacklist? Is there anyone else I should notify of these malicious accounts?