Hi Raj,
If you want to duplicate a bone with a mesh and have it mirrored, you could do this:
- animate one half of your character
- make sure that half is under a bone that contains all the bones and meshes that need to be mirrored
- duplicate the container bone, when it asks if you want to duplicate the keyframes, say yes
- set the scale of the container bone to -1 on one of the two values
done!😃