The angle of the faces differ a little. This of course could be photoshopped, but it’s more than just copy and paste.
Could it indeed be twins?
Same guy photographed in two different positions and photoshopped into the same image.
Looks like the blue stripe on the shirt is on different sides unless there is a stripe on both sides of the shirt and we can only see one side clearly.
It’s just mirrored (flipped horizontally).
It does seem odd to add a person. I think the other poster is right, it’s more likely he was pasted on there to cover up something or someone.