Might be a stupid question, and I have looked at some places but didn't really find an answer. Is there a point of having two of the same card? It looks like in custom decks if you only have one of a card you can play it twice. What is the point of having two of them? Should I just DE the second one for the dust?
Just starting out and trying to get a hang of things.
You got that wrong, you need two copies of any card to use it twice in the same deck. You always get two copies of the starter cards so maybe that's why you're confused. Legendaries can only be used once in a deck no matter what, so you're good to disenchant Legendaries when you have more than one of them and any other rarity when you've got more than two.
Although if you can afford it it's wise to keep dupes that might get nerfed in the future for the full de value, especially with Legendaries (400 vs 1600 dust).