Hi Kuzma!
1. The easiest way to have multiple instances of the same character on stage would be to wrap your rigged character into a Graphic Symbol and then create as many instances of that as you like.
If you need those to have different animations, you can right-click on the instance on the stage and choose Duplicate Symbol... from the context menu - then this internal timeline will become independent of the original while sharing the same rig/body parts.
2. If you need to have more than one instance of the same character on the same timeline, you will need to resolve the SMR ID conflict by renaming the rigs. Having many characters in sandwich mode will quickly result in tens and even hundreds of layers, which is impractical.
In this video you can see how rig renaming works (starts at 5:42):
A template of a rig is just a FLA which contains the rig. From that FLA you copy frames, layers or the Graphic Symbol container into your actual FLA where animation is done.
Hope this helps!