You can imagine Chaplin turning the conceit into a feature, Prince and the Pauper style. As the rich drunk he provides the film's funniest sight joke (from crying to mixing the drink) and the golf sequence is a decent set piece, but when the two identities meet there isn't so much material to sustain it (I was hoping people DIDN'T think they looked alike).
Somehow, Chaplin fully embodies his twin comic personae, deals with the issues of his own time, but looks at the audience with what could be 21st-century eyes. The last couple of seconds are splendidly defiant and uningratiating.
Although I prefer late Chaplin to early Chaplin - "The Idle Class" is hilarious. Chaplin's light-hearted barbs at the rich are always appreciated. prefer his darker, more savage critiques of Capitalism ("Monsieur Verdoux," etc) but - hey, It's Chaplin. What more needs to be said? He had more talent in his foot than most "actors" or "directors" have in their entire bodies. Even when he's bad he's great.