Help with bane weapons

[J-Rokka]

Sorry if this is covered in the book, but I didn't find it. Do two bane qualities stack?
Example:
Devon the fighter attacks a bearded devil (outsider-devil, evil, extraplanar, lawful) with his +1 evil outsider bane/devil bane longsword. Does he get +4 to attack and +4+4d6 damage, or does he get +2 to attack and +2+2d6 damage?

[Enkili]

J-Rokka wrote:

Sorry if this is covered in the book, but I didn't find it. Do two bane qualities stack?

Example:
Devon the fighter attacks a bearded devil (outsider-devil, evil, extraplanar, lawful) with his +1 evil outsider bane/devil bane longsword. Does he get +4 to attack and +4+4d6 damage, or does he get +2 to attack and +2+2d6 damage?

According to Mr. Jacobs only one bane is allowed on a weapon.