Two-weapon fighting and half strength to off-hand attacks

[Space Masters]

Another player told me that you only add half your strength to off-hand damage, but I'm unable to find this in the rules at all. The two-weapon fighting section in combat and the two-weapon fighting feat only talk about penalties to attack.

Can anyone point me to the rule about damage for off-hand attacks?

[LordKailas]

from the combat section

Light, One-Handed, and Two-Handed Melee Weapons wrote:

One-Handed: A one-handed weapon can be used in either the primary hand or the off hand. Add the wielder’s Strength bonus to damage rolls for melee attacks with a one-handed weapon if it’s used in the primary hand, or 1/2 his Strength bonus if it’s used in the off hand. If a one-handed weapon is wielded with two hands during melee combat, add 1-1/2 times the character’s Strength bonus to damage rolls.

Also, the feat Double slice which removes this penalty

Double Slice wrote:

Benefit: Add your Strength bonus to damage rolls made with your off-hand weapon.

Normal: You normally add only half of your Strength modifier to damage rolls made with a weapon wielded in your off-hand.

[Space Masters]

Thank you!