Conversion damage to skill question

Quick question: If I have two items that gives different conversions for one particular skill, does one get ignored? For example:

Handguards of Justice: 100% Physical Damage converted to Fire Damage to Forcewave

Mythical Arcanor, Blade of the Luminari: 100% Physical Damage converted to Elemental Damage to Forcewave

Fire Damage vs Elemental Damage. Do both get converted and stack damage? Or does one get ignored?

Goes 50/50 iirc. Meaning you get 67% fire, 17% cold, 17% lightning.

Thank you very much!