A: This situation could arise in any deck (or combined decks) where you have two cards which can give extra turns. For example, in Doctor Who Fluxx you have the Surprise My Turn Next (MTN) and the TARDIS Keeper. In Star Trek: Voyager Fluxx, there are two Timeships each of which can give you an extra turn.
The wording on most of these cards reads “The maximum number of turns you can take in a row using this card is two.” Another way to say this is that, no matter how many times you play this card in a string of turns, you’re only going to get ONE EXTRA turn in a row before someone else gets to play.
So, if you manage to play two different “extra turn” cards on your turn, yes, you’re going to get to take two extra turns, for a total of three. If, on one of your extra turns, you then manage to re-play one or both of those cards, they’re not going to give you more extra turns.
If someone tries to argue that the extra turns gained from each card are not “in a row” from each other (“The first extra turn was from MTN, and the second one was from the TARDIS, and now the third one is from MTN, and the fourth one is from the TARDIS again…” we would respond that this is an overly narrow reading of the rule, and goes against the intention of the restriction.
We want to avoid the abuse of these cards where one player takes a ridiculous number of turns in a row. That’s just not fun for the other player/s, and we want everyone to have fun. Only ONE EXTRA turn per special card.