It's been a while so --- from memory: You don't lose any fluid at all from one of them --- I think the top one that faces toward the rear. It's the lower one that faces to the front that generates all the fluid loss --- I maybe lost 2 quarts. Just drop the old filter into your container and screw on the new as quickly as you can.
I changed the small filter first, no problem. But when I changed the large one, the fluid gushed out. May have lost a quart or so of fluid. Went to TSC, got a two gallon jug of fluid, and topped it off. I did manage to overflow my oil drain pan!