I really can’t understand how to deal with this “feature”. I created some object by using extrude and loop cut tools. Everything’s okay with it, but if I want to edit this geometry - to move any edge or vertice, for instance, some really unnecessary faces come up. I tried to select these two vertices and merge (alt+m), but only one vertice selects and nothing changes.
Could you please help me to find what am I doing wrong or where could I messed up while modelling?
Ensure you don’t have any modifiers on your model (mirror or array modifiers)
Select all vertices and remove doubles (W / remove doubles)
Select what you don’t want and delete (X)
You may have screwed up when extruding but duplicating the mesh
Supply link to your blend file for review