The 'insert' in the card appears to be the box score cut from a newspaper. On the back of the card it says "This card contains the box score from Mike Schmidt's debut game". Mike's debut game was September 12, 1972. The card is serial numbered to 750 (this is numbered 274).
Could this be an clipping from an actual 32 year old newspaper or is it a reproduction? Could they have found 750 newspapers from 9/12/72 to take the clippings?
There are 25 cards in this set. Cards 1-20 have 750 copies, while 21-25 are limited to 100 copies. I don't know what the criteria is for the clippings on the other cards. If they are all debut games then most likely they would have had to come up with 15,500 old newspapers from very explicit dates. And some of these would be pretty old. For example, card #25 is Enos Slaughter, who debuted in 1938.
I believe that the box score is a reproduction. How hard would it be to do that? I think if the clippings came from an actual newspaper it would say so explicitly on the card back.
On the other hand, Beckett.com has images of 9 of these cards. They have the backs for some of them, and it looks like they are all debut game box scores. The box scores all look different, different type, different size, different layout. Maybe they are from actual newspapers.
Whichever, it's a pretty cool card.