Both sigs are no question authentic. I have this same photo signed. Fairly rare but they do pop up. Often times the sigs are faded, I jumped on an incredibly bold one. This one is nice as well. One of my favorite pieces in my collection. There's a pic of mine in the signature study.
Here's mine for comparison, sometimes Mick signed above himself, sometimes lower. And yes the few authentic ones I have seen all have this "era" Don sig which is my personal favorite style, 1986ish. Everytime I look at mine I wonder why Don's bat says #29?!?!!? lol:
Yeah this is the other photo of them that pops up occasionally. 99.9999% of the time this one is a reprint that people think is real. This one however is an authentic one. Nice piece.