You grow a second set of limbs (heads, arms, legs, tails, wings, etc.), though you retain only a single body. Any weapons you hold are also reproduced, though not ammunition or limited use items.

When making a full attack action, you may make one extra attack with each natural attack or weapon you are holding. The attacks are made using your full base attack bonus, plus any modifiers appropriate to the situation. (This effect is not cumulative with similar effects, such as that provided by haste or a speed weapon, nor does it actually grant an extra action, so you can’t use it to cast a second spell or otherwise take an extra action in the round.)

Additional motive limbs do not improve your speed, but each additional leg provides a +2 bonus to CMD vs. trip, as normal.

Multiple twinning effects don’t stack.