I think this is The Perfect Woman (1949) -- obsessive, genial, absent-minded professor type develops a life-like robot, named Olga. Olga receives far more attention from Prof than he gives his ward, niece Penelope. Now complete, Prof wants to test out his creation by hiring an unlikely couple of chaps to take her out on the town, to see if she passes muster. Penelope, pissed that the robot is getting the night out, swaps roles. Much hilarity ensures (yep, basically a one-gag movie). Weirdly, the plan includes putting the "robot" up for a night at a fancy hotel, which is where the undressing scene described occurs. Not a lot shown, but yes a very sexy situation played well.
Couldn't find the scene in question, although here's a snippet from the movie which pretty much sets up the back story...
https://www.silversirens.co.uk/patri...only-one-olga/