Corrupted Platemail Interactions

I haven't been able to find anything definitive to answer this question and I cant even begin to test this till much much later tomorrow. When wearing Corrupted Platemail, which converts 30% of your damage to Dark magic damage, if You deal a different damage type, say Frost as an example. Does it double dip into both potential buffs?

In my head it would but idk if anyone has tested for sure, cause I would imagine If you run a Frost Gun, the initial damage number is affected by any Frost Buffs, then you convert 30% of that number to Dark Magic, and then that number is affected by any Dark Magic buffs.

And if so, does that mean that any +Elemental Damage , +All damage, or +Gun dmg buffs would apply twice as well (to the frost dmg then the Dark Magic dmg)?