Actually, I am more confident on the signature on the magazine to the left. The one "To Martin". Not so sure on the other one.
They come together, so they are most likely both authentic or not
They must have been signed two different times then. The handwriting style also varies a bit. I'm confident on the "Martin". The other may be good as well.
These are not good IMO. I have consignments and in persons, going back to the 90's. These aren't even close IMO