Its in the Super Mario movie, his name is Mario Mario.

I'm honestly surprised there are people here who didn't know this. It's not speculation or unofficial rumours. Mario and Luigi's last name = Mario.

It has been pretty accepted that it's Mario Mario and Luigi Mario for quite some time now, I think it first came up in the animated series that they just retcon'd in there?

According to the movie, yes.

I think the movie said it first, and even though it wasn't canon, everybody went along with it, so I guess it's true now.  But it wasn't Nintendo's idea.

I think there's an old interview from the NES days in which this is confirmed.

Yeah, Mario Mario and Luigi Mario.

As many already mentioned, it possibly started as non-canon and now it's pretty much it for all intents and purposes.

it's a me, Mario Mario

Bowser's last name is Koopa, hence the name King Koopa.

According the the dumb arse super Mario bros movie Yes lol