Whenever you face two Evil/Wicked Masks, it is usually a fair assumption to make... you have a 50-50 chance of hitting either target when you bounce a single targeted spell off Reflect.
However, the reality is that this is not the case... which is a strange curiosity that started from the WSC port.
There is a very significant tendency for all reflected spells to hit the first monster in the first group.
A simple test consists of facing two Wicked Masks... allowing them to put Reflect status on the entire party and then casting a multi-targeted spell on all of the characters.
The normal distribution of damage should usually be pretty even, where both Wicked Masks should be taking 2/5 or 3/5 damage from split and recombined magics... occasionally having 1/5 and 4/5 damage and a semi-rare full damage to one Wicked Mask.
The problem is that there is some odd biases that cause the damage to shift primarily to the first monster on the field.
Single targeted magic has 2/3 or 3/4 chance to hit the first monster on the field... which has certain side effects and consequences.
Another way of testing this theory is through the CPU battle. Getting rid of the Defender helps... see what a spell like Holy or Flare is reflected onto the enemy... the chances that it hits the CPU is certainly more than 50%.