Hi, I’m new to these forums and I am currently working through the Bsod character animation tutorial and I am having a problem, I am on face animating but when I click one vertice to move, TWO are there and I have to double click otherwise one move but another one is underneath and the mesh looks unchanged. Also when putting X axis mirror on I click each vertice one by one and when it comes to rotating the “Jaw” parts of the other side moves with it but other vertices stay in place and I have checked they are symmetrical! Any help is appreciated! 
Select All (press A) and then press W / Remove Doubles. this will merge all the duplicate verts in your mesh.
Thank you so much for replying so fast! You’re a lifesaver!