If we think we can pull this off, we're Stark raving mad
The different clothes, the dyed hair, a ballcap, and sunglasses made for a reasonable disguise.  Probably wouldn't fool many for long, but long enough to get them where they needed to go.

He wasn't paying attention to the Stark Industries tour guide, though he would, to most people watching, look like he was.  Years of slacking off in classes and pretending to pay attention that way, at least, had paid off.  His real focus was on Anya, waiting for her to tell him when they needed to slip away, so they could track down...

Whoever it was that was impersonating him.  Or duplicating him.  Or...  he didn't know.  There were too many damn possibilities in this world for this kind of thing.