Black Noir puts on Homelanders suit before he does it. He also takes a bunch of pictures of himself slaughtering an entire family, and eating their baby. As fucked up as the show is, the comic is really vile. Anyway the fact is, Black Noir is a stronger clone of Homelander whose entire purpose is to be a killswitch for Homelander if Vought American ever feels it's within their best interest to off him. Supposedly they used their experience of raising homelander to better control Noir. But they still didn't get it quite right because the guy obviously goes insane. Because his entire purpose of existance is to kill Homelander and it's looking like it's never going to happen. So he does a whole bunch of awful horrid shit while wearing homelander's costume to try and trigger Vought into giving him the order.
So the footage of Homelander entering the room with Becka makes sense because it could still be Noir. What doesn't make sense is the actual Homelander reacting like it was him. If it was Noir, he should be confused and have no recollection of the encounter. I dunno we'll see where they go with it.