Kind of goofy. Is that a zipper on his forehead...?
Anyway, comics have lost whatever cohesive reality they might one have tried for. This could be undone the next issue without any explanation, there could be a long story arc explaining how the Punisher got back to normal or how this wasn't really the guy. Anything goes.
You can't resist the inherent pun. Frank Castle, Castle of Frank(enstein).