We all know how frustrating it can be to feel ripped off. I have made a few decisions regarding this.
I never check my category, that way I won't see anything I don't want to. Either something I think was copied from me or if I have an idea I won't think that I look like a copier myself.
I try to focus more on my work and less about others. It can be frustrating but it keeps me sane. I try to keep this quote in mind:
"Inspiration can be derived from those who have come before us, however an artist never copies the work of another for it is against the very spirit of what feeds our creativity"