OMG! How scary this must have been for you, I know I would have totally been freaking out as well and would have definitely called the police.
I'm so happy to hear it all worked out fine though and that the situation was nothing like what we all would have thought could have been one of our worst nightmares.
Honestly, my suggestion moving forward to not only avoid scary mixups and situations like this, but actual potentially dangerous ones that don't have such a good ending, would to be to get a good smart lock.
We just got this new lock a couple months back and absolutely love it! It syncs directly to my AirBNB calendar, sends guests emails with key code and instructions as soon as they book a stay, disables codes at time of check out (and accurately lol), and auto updates itself for me. I don't have to do a thing or have to worry about keys or anything myself, it's awesome. It also has a dashboard I can login to so I can change and edit codes, adjust settings, etc. so that I'm always in full control when needed.
Here's a link to check it out, I highly recommend it.
https://www.amazon.com/AirLocking-Smart-Lock-for-AirBNB/dp/B0759NPC5Y/ref=as_sl_pc_tf_til?tag=airloc...