I always do
Alamo/Costco. Costco only asks for the name of the principal driver. However, when I complete the online checkin on the Alamo site, I can add the name/address/driver’s license for the second driver. I am usually asked for the DL of the second driver (along with my DL and credit card) at the exit booth in the garage. I always do skip the counter and go directly to the garage when available (as it is at MCO). Since I also login to Alamo with my Alamo Insider number, the checkin pre-populates my DL and CC information, so all I have to enter is the second driver information.
When we rented with Alamo/Costco at San Diego, skip the counter was not available, but I had completed the checkin in advance as usual. There, I used a kiosk to avoid going to the counter. Had to scan both DLs along with the credit card to complete the kiosk checkin.
One other thing. Costco indicates that you need to show your Costco membership card when picking up the rental car. I have never been asked for this at MCO, and for many years I did not carry my Costco card with me. Then I was asked for it at TPA. Fortunately, my DW had her Costco card in her wallet the first time this happened, and she was on the rental as a named second driver from the online checkin, so I didn’t have a problem. The next time this happened, again at TPA with the same gate agent, I had my card ready, and now always carry my Costco card when renting a car, just in case.