When Using Throne room on a Throne room do you need two more action cards already in hand?

Question

In the base game Dominion, Throne Room lets you play an action card twice. The Dominon complete reference guide on BGG singles out the Throne room on a Throne room play for some helpful notes.

When you play Throne Room on Throne Room, this will let you play two other cards (each twice).

What I'm not clear on is if you need to have both "other" cards in hand already to be able to do this, or can the first card played allow me to draw the card I use on the 2nd Throne room?

Is this acceptable?

Hand: Throne Room, Throne Room, Moat, Copper, Copper
Play: Throne Room, Throne Room, Moat (drawing 4), Play Laboratory (which I've just drawn using the Moat), etc...

Or do I have to have the action card already in hand to make use of the "third" Throne Room created by duplicating the second card played?

Answer 1

In Dominion, the general rule is that you have to do everything on a card in order before you can play another card.

This affects Throne Room in an odd way, because it means you have to do everything printed on the card Throne Room tells you to play, then do everything on that card again.

Thus, when you Throne Room a Throne Room, you play one card and resolve it twice, then play a second card and resolve it twice.

TL;DR Yes, you can play the Laboratory you drew with the Moat as the second Throne Room's second play.

Answer 2

In Dominion, you can play a card instructing you to do something impossible; you just fail to do it and the game continues. So yes, you absolutely can.

More generally, you don't need to anticipate every game state that might happen if you play a card...in many cases, this is impossible anyway. You just need to follow the directions of the card, and skip instructions you can't follow.