weight painting copying to other side of mesh I completed one half of my rig and then copied it to the othr side of my mesh. when I finished only the left half of the rig(The part of the rig I finished first) moved the mesh, furthermore It moved the mesh on both halves of my human model. 
for example: when I moved the left leg rig both the right and the left legg were moved

I tried to fix it in weight painting, but when I began to paint the right leg it was duplicated on the left leg,

ps. yes I did use mirror modifier for my model
You probably have weight paint X mirror on, someone else already had a problem similar to your own. Answer If you go down to the first answer it shows you how to turn x mirror mode off.

Also it might save you some time if you do a general search for the tool causing your problem, I just searched "weight painting symmetry tool" and the first result was the problem your having now.

Hope this helps!