Very cool! Although it doesn't solve either of them perfectly for me (e.g. "HEY BUYS" instead of "HEY GUYS").

Would love to read more about how that tool works :)

That's very cool, but it doesn't correctly find the solution with the first string alone, it gives a wildly wrong answer (BEACH ASIONY MISE I WILLS BY WHO MY NEVER KISS HE-M UNDELIVE)

So don't trust that a system doesn't have a simple solution because an automated solver like doesn't provide a correct answer.

If you put them both in at once, the second output is 100% correct:

    VGYURYPEDFNCEPGEWELLPVNWRDCNFGMGXQEPPRGCBFIGLEMG. EQPMEIGQNVBAGBTFEGMSYNRKMNWEPBLWBYPSNWMQNFBDWEQVYNRCBFIGLEMG
    
    =>
    
    HEY GUYS I PROMISE I WILL SHOW UP MORE NEXT ISSUE MARCELINE. ITS NICE TO HAVE AFRIEND YOU KNOW IS ALWAYS DOWN TO RAP WITH YOU MARCELINE

Seems to be non-deterministic. Sometimes I get 'Hey Buys', sometimes I get 'Hey Guys', and sometimes I get:

   WEHXLHT I PROMITE IS IYYTWOSLP MORE FEUNITTLEMARVEYIFE. IN T FIVE NO WAKE AGRIEF CHOLD FOSITAY SAHT COSF NO RAPS IN WHOLMARVEY I FE

Yeah. It's not the best algorithm.

I looked for a while and http://www-i6.informatik.rwth-aachen.de/unravel/ seems to be state-of-the-art.