Gemling Legionnaire doesn't have duplicate stones working

But the mercenary has a Gaming Legionnaire class, which has a passive skill.

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Gem Studded: You can use two copies of the same Support Gem in different Skills

I added 2 spirit stones(Persistent Buffs) and inserted a support stone into each one -> Vitality

I was expecting to see +2% at life regeneration in the player's stats, but I only saw 1%
It's clearly a bug.
Why should a player have to waste time and pump 2 ascensions to be able to put stones into 2 skills, but get no effect from them?))
Please developers either fix this bug, or add the ability to change the class of the character, so that I do not have to swing the character again to choose another class, as this class does not work as it should