Gaban has to be the man with the burnt mark right? Like there's no fucking way this is just a coincidence, as young Gaban didn't have that
Maybe its just me but after Oda very specifically not drawing "Shanks" with a scar after talking with Gorosei, this shit with Gaban is absolutely on purpose.
Hes definitely that person, and like with twin shit easily explaining Shanks' dual persona, this being Scopper easily explains why and how someone could know where the FI Road Poneglyph was and take it specifically.
It being a brand new character just didnt make much sense in that context.