Game #3607252 on frankfurt. edit: Actually #3608195 on oregon (sorry)
On the previous turn, my opponent plays a Royal Carriage and a Hamlet.
With a Royal Carriage on my opponent's tavern mat, I got this prompt at the beginning of my turn:
Turn 10 - Dwedit
It's your action phase, you may...
• play an Action from your hand.
• Call Royal Carriage
If I chose to call the Royal Carriage, it played a Hamlet, my opponent drew a card, and I got the prompt of whether to discard things or not.
Then I did an undo. The prompt to call Royal Carriage returned, then I ignored it and played the rest of the game normally.
The prompt for me to call Royal Carriage did not appear again after that.
There must be some mixup, as that game (while including you) does not have any Royal Carriages or Hamlets. I guess finding the real game number is now impossible.
http://dominion.lauxnet.com/scavenger/?user=Dwedit helps to find the game number, when it was rated.
The bug occurs at:
Game Id: 3608195, decision index: 97
Thanks Markus! When I use dominion.lauxnet.com, I *never* see any game number. That is until now, when I clicked on the games and it gave me the game number. Maybe that could be in-cooperated into the listing itself (by whoever runs that site (you Markus?), which I guess is someone reading this site as well), as there is no indication that the listings are interactive.
Added: I loaded that game and as Dwedit and Markus said, that strange behaviour (error) is there. It seems 'obvious' that the game somehow retained the Royal Carriage trigger from Dwedit's opponent's last turn, where she followed up the Royal Carriage with a Hamlet and where she did not recall the Royal Carriage to replay the Hamlet.
Sorry about getting the game number wrong. It was #3608195 on oregon. I took the first one from the chat log instead of the most recent one by mistake.