Endurance Charge on Melee Stun vs Multistrike

Hello, I have a Marauder that uses a grande amount of Endurance Charges.
I wore Faster Attack Gem, but when I started using Multistrike Gem only the first attack gets Endurance Charge.
Why?
If the two other attacks are also stun.

This is a ban for Multistrike?
Or a fault, and nobody even noticed.

...
"Endurance Charge on Melee Stun is a support gem that can be linked with melee skills. When an enemy is stunned by a linked skill the character will gain an Endurance Charge."(PoE Wiki)
"Gain an Endurance Charge if you Stun an Enemy with Melee Damage."(PoE Wiki)

All of the 'gain X charge on Y' gems can only generate a single charge of each type for any single action. This means that no matter how many times you hit a single mob with an attack or how many mobs you hit with an AOE, you still only can get 1 charge per 1 click.
It works the same way for Power Charge on Critical or Frenzy etc.

same as with power charge on critical gem. Amount of charges is capped at 1/skill activation