A little glitch I've noticed with twin magic but was unable to check in more detail due to party members being far too impatient.
Take the moon surface "Crawler" monster as an example. It dies from a 9999 damage hit, such as a petrification hit. Hiwever, it survives a total 14,000+ damage from twin flare/comet.
I wanted to scam/libra/peep to see how much HP it had left, but my party refused to let it live till the next turn. However, this has happened numerous times in multiple parties, and I am now convinced it's a full blown bug and not a one time glitch.
If anyone would like to help me get some more defininitive numbers and data, let me know. My Twins are Krisofia (Mature White) and Minal (Mature black.)