Given the Rapid-Fire house rule, Two-Weapon Fighter (page 73 5th revised) for ranged weapons is significantly overpriced and is replaced by this these rules.
Two Weapon Combat is a 5 Point Special Skill similar to the the Autofire skills. It allows the character to attack once with a weapon in each hand for a total of two attacks for a full phase action. Each attack suffers a -2 OCV modifier. Off-hand modifiers apply however to the weapon in the character's off-hand (typically an additional -2 OCV). Thus the primary hand attack is taken at -2 OCV and the off-hand attack is taken at -4 OCV.
Attempting to use two weapons in each hand without the Two-Weapon Combat incurs the normal -3 OCV from unfamiliarity for each..
Note that Ambidexterity will counter some or all of the off-hand modifiers.
A character may Rapid-Fire one or both weapons incurring the additional modifiers of those maneuvers. Extra shots are counted separately for each weapon.
Example:
Donovan is rapid firing two pistols (and has the two-weapon ranged combat familiarity) at some rather frightening creatures that are already too close for his comfort. The modifiers are -5 (-2 base, -3 for second shot) for the weapon's two shots in his primary hand and -7 (-2 base, -2 off-hand, -3 second shot) for the two shots fired in his off hand.