Sneak attack from different sources

[e-Spaceshot]

I'm at a loss here. I'm not sure if it's just a kick in the nads to the vivisectionist archetype for the alchemist or it's a rule that will eventually be added to existing sneak attack places, but it seems to me that sneak attack damage comes down to the form of add all levels in classes that give you sneak attack and count that total as your rogue level for calculating sneak attack total.

Unfortunately this isn't stated anywhere else besides in the vivisectionist archetype. The rogue's sneak attack entry doesn't specify what happens when you get sneak attack from different sources, neither does assassin, master spy or arcane trickster. So in theory with RAW level 1 rogue/level 1 master spy or assassin (with enough of another class in between to make up the prerequisites) becomes 2d6 sneak attack, add in the other prestige class out of master spy and assassin it becomes 3d6 out of 3 levels. Then if you add vivisectionist (no idea why you would, but hear me out) you end u going back to 2d6 because you then start counting effective rogue level for sneak attack which is 4 levels.

This just doesn't make sense. Is vivisectionist not meant to multiclass as well into a sneak attack supplying class as any other or is it because it's the most recent (at least that I could find) sneak attack source that it just happens to have the most recent rules?

[Bobson]

Don't conflate sneak attack from prestige classes with sneak attack from base classes. They stack, but there is specifically no overlap in sneak attack progression. A rogue who just got a level of sneak attack, then takes a level of assassin gains sneak attack two levels in a row. One who instead takes a level of a prestige class which doesn't gain any sneak attack until 3rd level, after taking a level of rogue which doesn't grant sneak attack doesn't gain any sneak attack for three levels in a row.

That being said, I'm pretty sure that every base class which grants snack attack specifically stacks with rogue levels (and thus each other) to determine how much sneak attack they get.

[Bane Wraith]

Was this ever truly addressed or answered?

Because this Can be used to the character's benefit, if there's no amendment.

PRD wrote:

Sneak Attack: At 1st level, a vivisectionist gains the sneak attack ability as a rogue of the same level. If a character already has sneak attack from another class, the levels from the classes that grant sneak attack stack to determine the effective rogue level for the sneak attack's extra damage dice (so an alchemist 1/rogue 1 has a +1d6 sneak attack like a 2nd-level rogue, an alchemist 2/rogue 1 has a +2d6 sneak attack like a 3rd-level rogue, and so on). This ability replaces bomb.

There's no specification whether or not prestige classes count.

There's at least one class (Master Spy) out there that gains Sneak Attack, but at an inferior rate than the Rogue's

Technically speaking, they would qualify for the Vivisectionist's sneak attack ability.

Hell, if this ability somehow replaced their rates with that of a rogue, a character might even stand to Gain extra sneak attack damage, simply by investing one level in Vivisectionist. (Be honest, for the poison use and little boost to Craft(Alchemy) for some delicious poisons, who wouldn't? )