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Pretty positive that the embossed part is a Scoreboard logo. They had a bunch of cards like that they they bought back and had them autographed stamped them then redistributed one way or another.
I'm sure you already know this being a Big Mac collector, but it's obviously not issued by any card company as he was a UD exclusive for the (brief) time that he was signing.
If it is Scoreboard, be careful. When Scoreboard went under the embosser was sold and now thousands of fake Scoreboard autos are out there with the proper embossing.
Like a few others have mentioned I am pretty sure it is from Scoreboard as well. They released a set with Buyback autos in it and then after they went bankrupt a ton more starting showing up.