Or perhaps her perception of the two gifts is different from yours, OP.
Whereas you just wanted to give them each their favourite tipple, she might have felt self-conscious about her favourite being vodka while your other friend's is Prosecco, depending on her perception of the drinks or their pricing or other associations she might have.
She might wonder whether the other friend had rejected the vodka gift and that this is why you felt the need to go through the awkwardness of swapping them back - even if you turn up saying "oh, silly me, what a mix-up!", she might still be envisaging the other friend unwrapping the vodka and being horrified to the point of not even accepting it (especially if she happily enjoyed the Prosecco over Christmas!).
If she had said thanks for the gift initially, I probably wouldn't have taken it back from her once it was given - if the other friend didn't want the vodka, I would have replaced it with another bottle of Prosecco, but I don't think I would have requested the recipient give back a gift intended for someone else, especially not after Christmas when it might be too late for her to give it back.
I don't think she's upset about the mix-up itself, but about the way it's been handled and all the awkwardness around being asked to give back a gift she thought you'd bought for her.