Strange extra faces

Hello everyone!

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

“Remove doubles” helped a lot! I tried to repeat how I got this strange issue, but… couldn’t. Seems like I definitely overdid with extruding.

Thank you!