Bennu... Merging?

Time: 1:22 AM EST, 12/24/2014
Frequency: Only once
World name: Cactuar
Character name: C'thuuko Tohka
NPC name: N/A
Monster name: Bennu
Class/Level: DRG/50
Party or solo: Party, 8 people
In-game time: Around 12:50 AM EST, 12/24/2014
Area and coordinates: Final Coil of Bahamut Turn 3
Steps:
1. Get to the third phase of the fight, where the Bennu all revive and the boss goes untargetable. Four Bennu total spawned in the first two phases.
2. Kill Bennu such that there should be one large Bennu and two small Bennu.
3. After moving so that the revival of the large Bennu that was up at the time, there appeared to only be one small Bennu on the screen, except for a very very slight difference in the animation timings.
4. Tab targetting did not allow for me to target one of the two stacked small Bennu.
5. When the large Bennu that was on the screen at the time died, killing the one Bennu my group could see resulted in the death of both small Bennu.

Connection Specs
- Type of internet connection/provider: N/A
- Modem maker/model number: N/A

PC Specs
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Laptop Model Name: ASUS N56VJ
Laptop Model Number: N/A

Gamepad Manufacturer: Sony
Gamepad Model Name: Dualshock 3
Gamepad Part Number:N/A

Browser Information
- Name and version of the browser currently in-use: Firefox 34.0.5