Adam Kapowski's surname is never given in-game, to my knowledge, either, and Squigly is instead tagged by her real name (as "real" as these can be), Sienna Contiello. I'm not as versed in SG lore, but I'd suppose there's some standing reason for Marie to be tagged as she has. However, since she seems to have been named "Marie" even outside of her Skullgirl form, it may be better to reverse the alias, to allow accurate coverage of her human self. (This differing for "Patricia" and "Carol", since those names are drastically different.)
We could use input from someone more attuned to this hubbub, though.