you can also order a new door lock with a key code that matches the other door so that both doors are keyed alike and can use the same key. it's easy to replace the lock from the inside. just a couple more bolts to undo. our trailer has two doors that came with two locks using two different keys. can you imagine how many key you would need for you car if car makers didn't match the doors, trunk, and ignition?
as far as the keys for the storage bins, you can probably ask any other rv'er if they have some extras. it seems that all the stock storage locks use the same key. you can order them online also.
2015 cardinal model 3825fl
2015 dodge ram 3500 dually