For what reason would conspirators need to paste one black man over top of another black man?
As already explained, Mr. Mason, they mixed up Messrs. Lewis and Jones, and pasted in Mr. Jones' face because they needed something to take the place of the Coke bottle as it cuts across Mr. Lovelady's white tshirt:

Whatever portion of Mr. Lewis' face may have showed in the original Altgens, it didn't hide the bottle.
So:
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Theres an inconsistency with red shirt man in Hughes film when he’s holding up his hand (holding the speculative bottle) : His sleeves appear covering his forearm.
Only part of his forearm---------------as the hand is raised, the sleeve slips down a little

Now, look
very closely at the raised forearm in Cronkite:

Not even sure if the quick gesture being made by Red shirt man is a bottle brought to mouth. It could be just a salute to the POTUS.
We catch a glimpse of the bottle, which isn't being gripped right down at its base
The white shirt of Red Shirt Man is extremely white which suggests the thicker long sleeve white shirt that Lovelady was wearing when he was caught on film
On the 6th floor having removed his red plaid flannel shirt.
Do you mean Reddish Shirt Man in Hughes?

If so, are you seriously suggesting this couldn't be Mr. Oswald's white tshirt?
And is the white tshirt on the man standing behind and up a few steps from Ms. Maddie Reese not white enough for Mr. Lovelady's tshirt?

As for the sixth floor footage, what "long sleeve white shirt" on Mr. Lovelady? You are confusing something in the background for Mr. Lovelady's right arm. Watch what happens when Mr. Lovelady turns:
