I had the same thing happen to me on our last cruise. We got the tickets for one cabin, but not for the other. I called Carnival a couple of times and they said not to worry about it, as long as I had a booking number that was all I needed.
I was especially concerned because we didn't have any luggage tags or room number.
I went to the fun pass check in used the booking number and was all set.
At the dock, the porter gave us a list of everyone one the ship, we found our name, our room number, we put tags on the luggage, it was in our room right on time.
Don't sweat it have a great time.