Guardian seemingly dealing double damage with its melee attack (street brawl)

[absreaper]

The incoming damage tab says the guardian dealt 646 damage with two instances of damage, but as you can see here it only melee'd once. I'm not sure if I'm missing something because the incoming damage tab is often completely wrong, but I cannot figure out what could have possibly done at least 580 damage at once.

The only culprit I can think of is the allied ghoul that got smashed alongside me, but I don't know how exactly would it work.
The clip is taken on March 31st.