
Jester King |

From PFRPG; page 179
Multiplying Damage:
Sometimes you multiply damage by some factor, such as on a critical hit. Roll the damage (with all modifiers) multiple times and total the results.
Note:
When you multiply damage more than once, each multiplier works off the original, un-multiplied damage. So if you are asked to double the damage twice, the end result is three times the normal damage.
Exception:
Extra damage dice over and above a weapon’s normal damage are never multiplied.
Which damage would a character with a +3 strength bonus that is using a flaming longsword and confirms a critical hit inflict:
+1 Flaming Longsword (1d8+4+1d6 fire/19-20/x2)
A. 2d8+8+2d6 fire
B. 2d8+4+1d6 fire
Thank you.

Hartbaine |

Same set-up, character deals additional 2d6 points of sneak damage, confirms critical with same:
2d8+8+3d6(1d6 fire and 2d6 sneak attack)
Correct?
If you look under the 'Sneak Attack' class ability for Rogue it states that Sneak Attack damage is never multiplied with a critical hit.
Homebrew - In the games I run Sneak Attack damage is never multiplied, but the additional energy damage from things like a Flametogue are. So on a confirmed critical the +1d6 (fire) would become +2d6 (fire). Or in the case of a Bane weapon the additional damage is increased to +4d6 instead +2d6 when a critical is confirmed.
That's just how we roll, your mileage may vary. I run games that are epics, but very dangerous. PCs love when they score criticals and can min/max all the critical numbers they want, but they know certain 'boss' NPCs have done the same. They fear the critical.