Just wondering what are people doing with normal legendaries after you open the gold one?

Keep, disenchant, or maybe it depends do you need gold for crafting?

it depends; pure arena player keep them (even duplicates for bragging reasons I guess) and people with huge collections keep them, too (some play a "100% golden" deck or a "100 non-golden" one, others mix them).

People who need dust rather disenchant the golden one and not the regular one.

when i make golden i dis normal

Disenchant gold. To me dust is more important than a golden collection.

I was irrational regarding this, never disenchanted the gold one, even when I was starting!

I guess I'm a sucker for pretty animations

Keep both