I'm willing to believe the Soviet restrike theory, but I might be among the minority.
I actually don't think it that strange that such coin went undocumented for 110 years.
-First, the Soviet mints are very secretive.
-Second, they lost a lot of documents over the years so even if someone had access they might not find any records of such striking.
-Third, I don't believe that there has been much effort of any kind of new cataloging of Russian coins until the last decade, at least not in Russia.
-Fourth, gold coins were not easily traded/collected in russia due to prohibitive laws, and a lot were destroyed to get the metal, not sure if anyone was paying much attention in the west, I guess until the most recent decade they mostly traded as bullion.
Of course it could be a well done fake. Let's say the forgerer did not feel like making a new piece for the edging, but wanted to introduce a new pair of copied dies (which as I understand are easier to make but wear out quicker), so he struck a few dozen coins with the new dies but the with old edge. I guess if all of a sudden we hear about more mixed coins like this one we'll know it is a forgery.
Otherwise, I like the Soviet restrike idea!