This isn't regarding copied shirts, but instead copied game art (the thumbnails/icon I created for my game).
I e-mailed the DMCA address for Roblox and they said copying game art isn't against any rules, but they said they would look into the game itself as it was actually a "free Robux" scam game but it had the exact art & description as mine. The game later got taken down - not because it copied my art, but instead because of it being a scam game.
People copying the game art I spent my own time creating for my game doesn't break rules nor give a warning...
Those are bots trying to get robux by copying you. You should contact roblox staff if not leave it there. It is very dangerous to delete those by yourself. Same as games, if you visit a game for example Jailbreak, since its very popular and liked, the creator, badcc would earn a lot or money. So bots (sometimes scammers) will copy the front page but when you visit it (since if you visit it, the game gets even more popular), you see nothing in the game (but like a user's place).