Upvote:4
Since your new trip lies completely outside the validity period of your existing visa, you would just apply for a visa for that from the Danish consulate separately.
It is commonly said that you can't have two Schengen visas, but that inaccurate. What is true is just that consulates are not supposed to issue visas that overlap in validity with an already issued visa.
It won't hurt to explain the relation (or lack of same) to the Norway visa when you apply anew, and state that you still plan to go on that trip too.