GAMEPLAY - Ekko's Phase Dive Proccing Mountain Drake Twice Against Turrets

I noticed this in a Custom Game and after I noticed it I tried replicating it and it happened every time without fail.

Test: Go into a game with Ekko. Kill Mountain Drake Attack a turret, note Ekko's true damage to the turret. Activate Ekko's Phase Dive Attack the turret before Ekko's Phase Dive goes on cooldown. The turret will take double true damage from that attack alone.

My build:

I also tried to see if the same effect would work with but it doesn't seem to be that way.