Technically, this is not a rock-solid proof
Apart from having an alternate account (which is not a violation of forum rules anyway), this dude might have been framed (even if it was). How do you really know that MrDongyy is actually MrFreeRoMan other than by seeing someone liking to his Facebook and Twitter accounts? Disclaimer, I'm in no way affiliated with either of these forum members. Just come to think that people should be more responsible and stop witch-hunting (finding instances of plagiarism is not witch-hunting, just in case)
While alt accounts are allowed, ban evasion isn't. Mods have to decide whether or not there's enough evidence for ban evasion, and considering MrFreeR0Man (who is already evading his ban and thus breaking the rules by posting in this topic) didn't deny it, I guess it was true.