The concept of using a frame in a frame is an old one in photography. There are times it works well and then there are times that the inside frame may be superfluous. The first frame is your viewfinder (or rear LCD or that phone you’re staring at). The second frame is what is bracketing your central point of emphasis.
About my comment that sometimes the frame is superfluous… it’s addition by subtraction. A few leaves or branches around a shot of a beautiful lake may create a frame of some interest but ask yourself if the picture is really better with the frame. Just imagine in your mind’s eye if adding the frame is subtracting from the focal point of the image. Superfluididity aside, here are some of my frame in frame photos.