Ezreal ultimate

Just played a game where I landed an Ezreal ult on the enemy LeBlanc at around 50% health AS THE FIRST HIT, dealing damage and dropping her below her passive % hp threshold, upon the stealth dissipating, there was a little less than passive heatlh LB and a near dead one, as it turned out, the near dead one was the clone. This confused me a bit but I dismissed it. This then happened again except the ultimate WOULD HAVE KILLED HER, but left her on about 14 hp and killed her clone. My only theory is that on a hit that will activate LeBlancs passive, the damage dealt via ezreals ultimate is DECREASED (as per the ability conditions, multiple hits reduces damage to a minimum), because the ultimate counts the clone as an additional target, BUT WILL PRIROTISE THE CLONE FOR DAMAGE DISTRIBUTION FIRST RATHER THAN LEBLANC HERSELF, DESPITE LEBLANC BEING THE ORIGINAL AND FIRST HIT OF THE ULTIMATE.

I do not know if this is intentional, but it really is quite frustrating.