Well, you might be able to claim them for both cars, but you'd need to check the specific requirements on the T1-M form to be sure. If it asks for total kilometers driven, it's possible you'd need to include the distance for both vehicles. As for the return trip, it's usually only the moving trip that counts, not the way back.
It's a good idea to keep detailed records of your travel, including receipts for fuel and any other expenses related to the move. I once read a helpful article at https://threemovers.com/long-distance-moving-cost/ that might give you some insights on typical expenses and what you can claim.
