Then, these showed up on Ebay.
Donruss went into bankruptcy in 1998. Apparently the company was going to release a second series of the base set as well as some other sets. They were going to expand on the Crusade set with players that had Call to Arms cards getting base Crusade cards, and vice versa. So, these Call to Arms cards were produced as a second series to the Alomar cards. But they were never released due to the bankruptcy. Afterwards, someone acquired a bunch of the stuff that was never released and started sending them out into the market. I have no idea how many of these cards are out there, but here is the Green and Purple cards. They are possibly one-of-a-kind cards. I asked the seller if he knew whether there was a Red, but he had not heard of one. He did have Red parallels of other unreleased cards though, so it may be out there somewhere.
These are rather amazing cards to add to my collection. There is no official record of them existing, so they make great additions to my collection.