I think something like that should have been foreshadowed if it were to happen though. Else, it could feel like an ass pull, even if it was logical.
That's an understandable concern assuming it was premeditated like in Alabasta but I (personally) was only really referring to physical evidence functioning as proof of identity. Meaning it doesn't need to be a flashback showing us they decided ahead of time to keep bounty posters for reference, but rather something like Usopp already having them in his satchel and thinking to check them or just grabbing for a weapon and seeing them. It could also serve more than one purpose by allowing him to see his Sogeking bounty and, like at Thriller Bark, have him confide in Sogeking for help. Granted that's just me taking the idea and running with it, so there are a lot of ifs involved, but anyway I'm just saying the idea has merit.