In 1921 a coin dealer, Zerbe, had influence at the mint. As a result, he was able to have some proofs made of the Morgan dollar. (There are also Chapman proofs known). As for your question, I would assume that those are the dies for the proof coins that were struck.
Quoted from PCGS site: *** Proof examples of this date are quite different from those of earlier dates. Two Proof versions of the 1921 Morgan Dollar were struck, both apparently at the request of individuals outside the Mint. [SIZE=-1]The first version, known as the "Zerbe" Proof, was struck for the noted numismatist, Farran Zerbe, who supposedly had a fit when the new Silver Dollars of 1921 turned out to be a resurrection of the Morgan Dollar type instead of the new Peace Dollar type that he had promoted. The exact mintage is unknown but the figures bandied about in the past have ranged from a low of 20 to a high of 200. PCGS has certified 78 "Zerbe" Proofs, the finest of which have been 7 PR-66's. Breen noted that most of the "Zerbe" Proofs he had seen had been cleaned or scrubbed, but his experience conflicts with PCGS' findings (PCGS will not certify cleaned or impaired coins). [/SIZE] [SIZE=-1]Breen offered some die characteristics of the Zerbe strikings, but be wary, as circulation strikes also exist from these dies:[/SIZE] [SIZE=-1]"Obv. Small die scratch up to r. from left tip of serif of left upright of second U in UNUM to border. Left base of first 1 above center of dentil, r. base of second 1 slightly r. of left edge. Central details far sharper than on regular uncirculated pieces. Rev. Very faint recutting visible on left upright of T in UNITED. Horizontal die file marks plainly within ribbon bows and at left and right of them; vertical die file marks at inner berries nearest to left base of N and T in UNITED. Eagle's breast feathers unusually sharp. Brilliant proofs as in 1904 and earlier years, carelessly made..."[/SIZE] [SIZE=-1]The second Proof version is the so-called "Chapman" Proof, named after the Philadelphia coin dealer, Henry Chapman, whose name appears on a Mint invoice (dated June 11, 1921) selling him "10 proof silver dollars 1921". For years, the mintage was thought to have been limited to only the ten coins, but now we know that additional "Chapman" Proofs were struck. PCGS alone has certified 40 examples, the finest of which is a single PR-66 that far outshines the 13 PR-64's that are at the next level below. The only Proof Cameo example graded by PCGS is a single PRCA-64. "Chapman" Proofs are super brilliant and have only 16 berries in the wreath on the reverse, as opposed to 17 on the "Zerbe" Proofs. Additional die characteristics include a hollow area around Morgan's initial on the truncation line on the obverse (caused by die polishing) and light die striations around UN, AM, and RICA on the reverse[/SIZE] *** Hope this helps
Editorial note. The following: (PCGS will not certify cleaned or impaired coins) Is flat out wrong. Respectfully...Mike
According to a recent magazine article, there is doubt among some researchers/numismatists whether the Zerbe proofs are actually proofs, or even exist at all. Not my speciality, but would make for some interesting research.
No it doesn't conflict or at least their isn't enough data to prove a conflict. At that time PCGS wouldn't certify cleaned/damaged coins so the only thing in their pop reports would have been the uncleaned ones. That doesn't mean they didn't see others that were cleaned but not counted. (Also for rare coins cleaned /damaged coins often DID get slabbed.)
