If another artist appears to have created a very similar work to one of yours (or worse, is using your images or making exact copies), that can be alarming. Whether it violates a copyright is not something FASO can legally decide. 

If you feel your work has been copied, you may only need to contact the other artist directly. It may be an honest misunderstanding or ignorance of what's acceptable. The other artist will often respect your wishes and remove the similar piece(s). 

Regarding FASO removing the content: 

We can only legally remove content if it is a valid violation of the DMCA. If you wish to file a DMCA Takedown request with us, Click Here to see the information and procedures that, by law, must be followed.

If we receive a valid takedown request and remove the alleged infringing content, the artist whose content has been removed has the right under the DMCA to file a counter-notice to have the content reinstated (if they feel it was removed by mistake or misidentification). 

In that case, where FASO has received a valid takedown request and a valid counter-notice, we have done all we can legally do. Further disputes would have to be settled directly between the two parties without FASO involvement.

Interesting article on the subject, published on artsy.net:
How Jeff Koons, 8 Puppies, and a Lawsuit Changed Artists’ Right to Copy

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