But there was no real Benny Russell. The Benny Russell visions were clearly metaphors, fantasies. The second one was a trick by the Pah-wraiths to make Sisko lose faith in his sanity and purpose, and personally I think the first one was too.
1. I really don't see why you would argue that the vision in "Far Beyond the Stars" was sent by the Pagh-wraiths to dispirit Sisko. The entire point of that episode was that he was already
demoralized, but that being reminded of the oppression of his ancestors and the value of the freedom he was defending from the Dominion was what re-ignited his spirit. It seems probable to me that this was a vision from the Prophets.
2. The novel Crucible: McCoy - Provenance of Shadows
establishes that there was
a real Benny Russell in the mid-20th Century. Of course, the Crucible
trilogy is not set in the same continuity as most Treklit novels -- but I personally think there's a reasonable argument to be made that Benny Russell may have existed in the "real" Trekverse and that he may have been given visions of the 24th Century to inspire his writing by the Prophets -- who perhaps deliberately sought to link these two men's lives across the centuries.