Fatal and "damage on a crit"

[hyphz]

The critical hit damage sidebar says: "Don't double extra damage that occurs only on a critical hit."

The fatal ability says "on a critical hit, all the weapon's damage dice increase to [the specified] die size instead of the normal size."

Does the fact that the Fatal ability has modified the weapon's damage dice means that they now count as "damage which occurs only on a critical hit", and thus are not doubled?

[lud]

They are still "weapon's damage dice" and "weapon's damage dice" are doubled.