Some of the mint sets that I have received — those for 1975 & 1976 specifically — have both P & D coins in the US Treasury envelopes that come with the coins. Some of these have light orange printed cards describing the set in the envelopes, others don't, but these are often only Philadelphia minted coins. My question here is concerns whether there was a time when the mint sent out ONLY the P coins in the mint set, OR, have the ones I have received actually been proof coins that were sold to me as a mint set? As I look over the many listings, there seems to be only a few that have both P&D coin sets, most are just listed as mint sets with only one cellophane set, not two. In this link of an auction for multiple year sets, the seller pictures what I believe are BOTH coin sets that are from original mint sets and others that are from proof sets. He does not distinguish these in his auction title, but it is obvious that there are those that have red seals, others with blue and some that are clear. I note also that there are different sorts of "stickers" on the cellophane, and I think these distinguish proof from uncirculated regular coins. Is this correct? https://www.ebay.com/itm/17-United-...862534?hash=item48a968cb06:g:ONwAAOSwAPtamz1e There isn't much at all in the Red Book, and no pictures either. I would appreciate knowing about the history of these sets, whether the mint sets have always had P&D or whether these were separate items years ago. Thanks for the help.