That's not how it's done -- you duplicate the layer with the over-the-shoulder shot. You put the duplicated layer ABOVE the corner pin layer. Oops! You can't see the corner pin any more! How do you fix that? You animate a feathered mask around the shoulder and any other parts of the shot that you don't want to be obscured by the corner pin. The process is known as rotoscoping.... and it's not much fun. It takes a lot of time and detail work.
Sorry! No magic wand solutions for this kind of shot!
No, you are completely wrong. I don't duplicate layer with the over-the-shoulder shot and then I start to deleting parts of orange shoulder. I did this differently.
Please, read carefully what I wrote and shown on screens. When I finished corner pinning I start to deleting A PART OF CORNER PIN IMAGE. Not duplicated layer of my shoulder shot like you talked. So I still didn't get answer of my question why we can't use a MASK on obcject modified by CORNER PIN?
See agan on that screen and look what happened. A corner pinned image is deleted by mask but mask even doesn't touch this image!
I wonder why...
You have to pre-compose the corner and layer and then do your mask.
The other option is to put the mask on the other layer.
The last option is to use the track matte.
You just have the wrong workflow, that's all. If it were my project I would duplicate the footage layer then Roto out just the shoulder then put the corner been in the middle. You'll be able to get a better result and do things like like and some light wrap to sell the composite.