I would say that interpretation 1 is correct. On a crit, you roll the dice two times (two separate rolls added), but with a wild attacker, you can only roll back the dice once a lap. So you can re-roll ordinary dice or critical dice, but not both.
To speed up the game, you can roll all damage dice at the same time.
This sentence would further imply that the rolls are designed as separate rolls, and that rolling them at the same time is only practical. Using dice of different colors for regular and critical damage would still allow you to cast them at the same time.
By the way, with this interpretation, the interaction with Brutal Criticals of barbarians (and Savage's semi-orc attacks) is pretty vague (especially if you use a 2d6 weapon like a swordfish.)
- never restart brutal criticism,
- can relaunch them instead of ordinary critics or dice,
- can raise them with dice or crit
- House rule: On a crit, roll an extra set of weapon dice and remove the lowest dice set from the total. For example, a level-4 half-oric barbarian with Savage Attacker and a large swordfish would place a crit on a 7d6 roll and drop the two lowest dice. With a large arch, he would roll 4d12 and drop the lowest die.
On the other hand, raising all the dice on a crit is certainly more fun, if that 's what you like.