How does the game decide who goes first when two toons are BOTH granted 100% turn meter?

Say a QGJ and Rey get the TM boost from Phasma's VM and they were both above 50% TM. Both toons now have 100% TM and are ready to go. It is now coin flip as to who is going to go first out of the two. That's why in droid teams when people talk about working with mods to decrease gaps and have certain characters go first, they will only have one character (HK) above 100% and then 88/86 as close as possible without going over 100 to maximize damage.