I think you're confusing liners and inserts. Liners are very thin, usually papery disposable ones or one layer of fleece (like a blanket). You use them to keep baby's bottom dry and to catch poo so it's easier to dispose of. Liners are NOT absorbent. An insert is thicker and very absorbent. They can be made of lots of different absorbent fabrics like microfibre, bamboo, hemp, cotton...
I think the two 'liners' you got with your nappy are actually inserts - they are absorbent. If you have naughty baby pocket nappies, the inserts go inside the pocket. That way you have the waterproof outer, then the absorbent inserts, and then the fleecy lining. The fleecy lining means that you don't have to use a liner to keep baby's bottom dry. Some say that using another liner on top of that will make the nappy not work, but I have never found that to be the case so you could use a fleece or disposable liner on top of it to catch poo.
As for how many inserts to use, it's different for every baby. Some will only need one, some will need two. I'd try two and if it's dry after a few hours you might only need one. If you're using both, they both go inside the pocket. Hope that helps.
