I'm pretty certain both of you have to upgrade to the Premium Plus for the exact reason of what you are proposing. Obviously there could be some medical exceptions to this, but in general that is the rule.
That aside, Premium Plus gives you some power and notability amongst the bar tenders, so once they get to know you, bringing 2 of anything you want on Plus is just not an issue. I have done it with Starbucks, water, energy drinks, etc. The caveat being, the bartenders knew that it was me and my wife and that we both had the Premium Plus. It is possible they police it more if they recognize only one person in the cabin has the package. Remember "sharing" is not allowed, even though I'm sure people get away with it.
So technically, if you are able to only get 1 person on Plus in the cabin, that one person "should" have the ability to order 2 unopened drinks and bring them back to the room.