I had done single riggings with mirror methods were successful. Now, through tutorial that I could get whole armatures to mirror automatically. I played around and follow steps from tutorial… So, I put cursor in middle for duplicate armatures to move left side. I use 3D cursor mode. I selected armatures then duplicate them then use CTRL+M. I also make sure duplicate armatures positions by using ESC. I did X key. The duplicate armatures moved to left but look asymmetry. I struggled to make it right. Obvioiusly, I accidently click somewhere that cause not properly symmetry even i use CTRL+M.