Upvote:3
In all cases I have gone through customs after a flight, I had time between collecting the case and walking though the customs check.
So you will have time to get the bottle out of the case and stick it into your hand luggage or an extra bag.
Upvote:5
Limits are explicitly per person, as far as I've ever seen, not per bag.
The customs officials might challenge your assertion that you each own one bottle, based on the fact that they're in the same bag, but you ought to be able to rebut the challenge. For example, if you have separate receipts for the items (especially if they were purchased with bank cards, so you can prove who bought what), that would support your position. It also helps that you also have a good reason for packing your separately-owned bottles in a single bag.
You may be more likely to succeed if you declare the goods upfront, so your assertion that you each own one bottle does not appear to be an attempt to trick the customs officer.
The ultimate answer to the question perhaps depends on the attitude of the customs official and the legal climate of the country you are entering.