Plagiarism?

Just wondering how we deal with proper artist tags to certain works, for example taiwangenjumin has works on his profile that are clearly not his but have been uploaded and approved (check his profile on pixiv and you'll notice inconsistency in styles). Example post #1766342 is really done by artist DARKPALETTE on DeviantArt (http://darkpalette.deviantart.com/art/Bigthunder-469206943) and post #1764308 is done by Johnsonting also on DA (http://johnsonting.deviantart.com/art/NEO-JAPAN-2202-KIKAI-YOHEI-436385738).

The question is how should we be going about tagging/approving these works? Obviously I can imagine tagging with the appropriate artist should be done but any other things to be aware of?

Attempt to upload the original. If it gives an md5 match and redirects to the already uploaded image fix the source and replace the artist. If it doesn't, parent to stolen work to the original and flag the plagiarized work.

I can't find taiwangenjumin. Is this the right profile? I don't want to report the wrong one.

Yeah that's the correct one.

Done. I guess that pixiv account will be gone quite soon.