Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I used to see this a lot in 3rd edition for some reason, but not so much any more.

I don't mind if you roll two dice at the same time, but only if:
1) you tell me exactly why you're doing it
2) you roll normally for twin-linked Gets Hot weapons
3) you roll normally for multiple twin-linked shots.

The reasons for these have already been given in this thread.

As such, I wouldn't bother doing it myself. It's really not hard at all to just pick up any misses and roll them again.

As Jidmah said, the best thing is to roll all your "first chance" rolls, then pick up and roll the misses.

When rolling for twin-linked, the probabilities are not separate. As pointed out above, you only roll your reroll if you miss your first chance roll. This means the second roll is dependent on the result of the first roll. A different equation is used for dependent probabilities.

The issue of dependent probabilities also arises for poisoned weapons in melee, and for Tyranid monsters with scything talons.

If your dice aren't 100% fair then you are rolling the 'bad ones' Ie re-rolling the ones predisposed to 'miss' already

It's like why after you roll 20 to hit, 10 to wound and you opponent makes 7/8 3+ saves - you've culled the bad dice for him!

Kill - they are not dependent, as the order is not important. (for the base case, non-gets hot! or similar type of weapon)

You are looking for a simple hit result on either dice. IF you roll both dice together, a hit on either is a hit, and yields the same probability if you roll one then another or if you roll two at once.

P(3+ on TL 1 shot weapon) = (2/3+(1/3*2/3)) = 8/9 = P(3+ on 1 of 2 dice)