Mapmaker

[dominionplayer1]

So I just played a really frustrating game where I am pretty sure there is a bug. The card Mapmaker says that when a player gains a victory card then you may play this from your hand. What happens, though, is that if the player draws another Mapmaker as a result of this Mapmaker reaction they are then allowed to play that one. This appears to be an error, as this card was not in your hand when the victory card was gained and therefore should not have triggered its reaction. If, however, a second victory card were gained, you should be able to react again with those Mapmakers you added to your hand, but you should not be able to react to the first victory card gain.

[Ingix]

The behviour you saw was correct.

Ultimately it boils down to the fact that when you play any Reaction card that draws you cards (like Mapmaker oder Diplomat) in then physical card game, any opponent has generally no way of knowing if the second copy was in your hand initially or if you just drew it.

It could be handled as you suggest in a digital game, but since the digital is supposed to run using the pyhsical card game's rules, it follows those.

It's a very longstanding rule/ruling, going back to a card from Intrigue's first edition, Secret Chamber:

You may reveal the same Secret Chamber multiple times when reacting to an Attack; for example, in response to an attack, you could reveal Secret Chamber, draw a Moat and a Copper off the top of your deck, put back two coppers, reveal the Moat to be unaffected by the attack, and then reveal Secret Chamber again to put either the Moat or the Secret Chamber back on top of your deck.

This is from the dominion wiki at https://wiki.dominionstrategy.com/index.php/Secret_Chamber