You posted three, not two.
And there are four or five others used. All with differences.
The first two you posted. I addressed reasons why they may appear different(cgi progression or unfinished or just plain design change, part Pract shot part cgi ect) and your response was "no from same trailer". Which means nothing. Trailers are cobbled together footage. And even if it where all shot on the same day at the same time and then all the cgi added and polished all at once by the same artist..my explanation still works. (Which they where not all done at same time even in same trailer)
Then you posted a third unique photo.
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That's 8 heads all with changes. Four of those photos are the ones you posted. All four are different in some way. I posted others just to make my point. One has the antena things reversed even. (The one where he's blasting someone) All screen grabs. I have five or six more. So, are there a dozen versions of ultron? Or, do you think maybe I had a point?