After I mirrored the vertices, the bones are not independent

Hoi, I wanted a smaller texture so I used the Mirror function in Blender to cast the UV texture on both sides of my animal model. The problem is that the model has bones which are needed for animations - after the mirroring even the Bones texture (?) was mirrored (the texture where I say which vertices should move with which bone). So it was not possible for me to move the left leg with the bone without moving the right leg. I can’t do a walking animation like that. Is it somehow possible to make the bones independent? The model is here if some is interested: Direct link:

Edit: Second picture: If I subtract the right legs, the left legs will be black/subtracted, too.

This rig is a bit messy: The first armature modifier is empty an needs to go away. The mirror mod. must come before the armature for it to mirror the vertex weights and, above all, the bones need to have the correct name structure (xxx_L for left bones, xxx_R for right ones).