The Confused condition states:
A confused creature is mentally befuddled and cannot act normally. A confused creature cannot tell the difference between ally and foe, treating all creatures as enemies. Allies wishing to cast a beneficial spell that requires a touch on a confused creature must succeed on a melee touch attack. If a confused creature is attacked, it attacks the creature that last attacked it until that creature is dead or out of sight.
As I understand it, this means that if one confused person rolls "attack nearest" on its confusion roll (1/4 chance), and that target is also confused, both it and its target will be compelled to keep attacking for the duration of the confusion, no longer with any chance to do nothing, act normally, or hurt themselves. Normally there would be a 1 - (.75)(.75) chance of that happening for two properly positioned targets, or 43.75%.
Am I right about this? If so, the following seems to be true and a better option than I thought Id Insinuation offered.
The Id Insinuation line of spells provide, for level II and up, that you can force two rolls on the confusion results table and pick one of them. So it sounds like Id Insinuation II gives you a 75% chance (assuming you can't have the same result twice) to force two targets who are closest to each other (an no one else) to attack each other as long as you concentrate plus one round. You can always prevent them from acting normally on that first round (again assuming you can't have the same result twice with no actual choice). That's not bad for a 3rd level spell, although both have to fail the save.
Id Insinuation IV lets you pick the result on the first round, so you can absolutely force everyone (up to four targets) to fight to the death as long as they fail their save and have proper positioning. You can then do the pick from two rolls on subsequent rolls, so you can try to influence additional fights as original targets die.
Yup, if two are confused and one hits the other they will fight to the death.