I'm going to guess there is an internal reflection involved. I say this because on the right photograph, I see some "textures" inside the top right portion where it is additionally exposed.
Because two photograph has the same portion "fogged", I'm going to guess there is a leak somewhere on the camera. Because there's some reduction in contrast, I'm going to guess your lens may have haze.
If you are testing a new equipment, there has to be only one element (the camera) that is in doubt. If you suspect the film was fogged before it went into the camera or fogged during development, it's going to be nearly impossible to test the subject camera.
Playing with old camera is fun but is also frustrating. I know because I do the same myself!