I've seen this assertion, but it isn't convincing. There isn't anything to back it up. They do look somewhat similar, since it's the same guy with the same face shot from approximately the same angle. But there are also subtle differences.
Whoever is wearing the Kenyan’s face appears to be a lot taller than the Kenyan.
Well, from what little we know, Barack Sr (5'9") should be about three inches shorter than Stanley Armour Dunham (6'0" ? Is there a cite for this? Do we know he wasn't closer to 5'10" or 5'11"?). Sr appears at first glance to only be about an inch shorter, but he is standing closer to the camera than Dunham. We also can't see their footwear, which could easily account for an inch difference or even more.
I'm not sure what you think the purpose of such a manipulation would be, anyway. As it is, the photo completely undermines the DREAMS myth of Ann's parents disapproving of Barack Sr. Yet here is Gramps yukking it up with Barack Sr with Ann nowhere in sight.
Phil is the one who figured it was the same face. Looks exactly and precisely the same to me. That photo has been taken apart on other threads and is a crappy patched together photoshop job. No telling who or what or where or when it was taken. It’s a stew.