Yesterday I got a message that my submission (180621980) for problem 1748C - Zero-Sum Prefixes coincides with mod_07's submission (180638882). I admit they are kind of similar but it was just a simple problem and I think that much similarity is normal.
Weirdly my solutions aren't skipped after rejudging, (in fact I got another +187! Wow! message) but his solutions are. I can assure you I did not cheat and I did not supply him my codes. Mentioning MikeMirzayanov.