Oh ho ho hoooooooo
That's a special key given to reviewers; frequently they contain multiple games by the same publisher so that a publication can do a bunch of reviews for the various recently released and upcoming games. The games expire after a period of time so they aren't just "free" forever. What this (probably) means is that Ubisoft gave someone a key with the intention that it be used for a review, but it has somehow been leaked. It may not necessarily be for Far Cry 5, but I would bet a pretty penny that it is.
Either the reviewer did use the key and then leaked it anyway, or they never intended to do the review they just thought they were getting a free key, but the key expired so it's no good. Both used keys and expired keys report "duplicate code" errors, so you can't tell the difference.
ANYWHO, it may be worthwhile contacting Ubisoft and telling them you won a reviewer key for what you think is Far Cry 5 and that they probably want to know so they can blacklist the reviewer they sent that key to in the future. They *may* be happy and give you a free copy "for your trouble"; most likely you'll get at most a thank you, but it doesn't hurt to try.