Yes. A sub with two engineers, if it wins combat, will give you 100% of the losses back.
A pretty powerful combination for attacking. To defend against it, a Double Agent would be especially useful as the defender gains two promoted specialists for the price of one. It could also be defended with a single Assassin, the attacker would need to decide if it's worth the loss of all specialists in the attack to carry it out.
"If we don't know what we are doing, the enemy certainly can't anticipate our future actions." - Colonel Goodhead