Well, Dark Yuugi/Atem seemed less extreme with his Penalty Games compared to his manga counterpart, so 5Ds Ushio is probably the same person that appeared in flashbacks in the anime's universe.
Also, just for information's sake, what basically happened in the manga was that he was playing a Game of Darkness with Yuugi with a theme based around greed, involving a knife and a stack of yen bills, and he decided to stab Yugi after he found out he had pretty much no control over his greed. After that, Yuugi inflicted the Penalty Game "Illusion of Avarice" and he pretty much went insane in public, thinking piles of leaves were piles of money.
The only reason I don't think it's the same Ushio is because (from what I've seen of 5Ds) he doesn't seem to be anything like the Ushio from the manga, which is the only source to base his original personality from seeing as he wasn't shown in anything other than flashbacks. Again, the anime may be different.