I was playing a game today where I played a Crown then a Lighthouse to get two actions, but when my next turn came around, my Lighthouse was not returned to play for +1 coin.
Hrm, just tried it with a bot in game #4631984 and it worked twice as expected. Wish I had remembered to write down the game number when it first happened.
You might be able to find it here:
http://dominion.lauxnet.com/scavenger/?user=refried&num_results=10
I took the liberty to look through the games and apparently it was game #4629643. Refried played Crown+Lighthouse once (on turn 7) and the log shows on turn 8 that two Lighthouse effects happened (with Ingix replacing refried in my reload).
Turn 8 - Ingix
I starts their turn.
I gets +1 Coin (Lighthouse).
I gets +1 Coin (Lighthouse).
Replaying the game from decision 60 (sometime in opponent's turn 7) had my/refried turn 8 start with Crown+Lighthouse in play, and 2 coins added to my wallet (as it should be)
So I *think* this is refried misremembering a certain situation.