Insulin Return?

I ordered some mail order insulin about a month ago (humalog for short and lantus for long), it arrived, and then last Friday I received another set of insulin.

I didn’t order this second set and after getting billed a crazy amount of money and calling my provider, they stated that they sent me a replacement because the first set did not arrive within 24 hours (and will reimburse thank goodness). They said they are sending me a package slip to have me send the original set of insulin back because I shouldn’t use it. I have a couple questions about this so if anyone can assist I would appreciate it!

So, do I have to return the insulin? And if not, can they charge me for it? I don’t want to return it if they are going to destroy it because it arrived cold as they put ice in the packaging.