Stranded vs Solid Copper

The plastic box was buried in the wall so far that the electrician used 2 + inch screws to connect the receptacle to the plastic box. When I plugged my Silnote cord  into the receptacle it pushed the receptacle back into the wall and broke the plastic cover.
i could have mounted the metal box right over the existing box, but I thought this might afford me the chance to gain some flexibility and expand the number of outlets to two.

You can get outlet extenders and / or spacers to keep the receptacle from pushing in and breaking the face plate. You could remove the old box and install a double gang if you want 2 receptacles in that location or install another box and run a wire from the existing box to your new box if you want them in seperate locations.

The electrician should have used an extender or spacrs to make the receptacle tight not simply use the face plate screw to hold it but nothing new there. The patio home I moved in this year I went around and had to fix about half the receptacles and switches with spacers to tighten them. 

Thanks for the input... you've given me some new ideas. I'm going to mount an exterior metal box with a solid cover over the top of the existing outlet box. Then I'll run a piece solid cooper romex in conduit horizontally over to another surface mounted box with hospital grade receptacles that is directly behind my rack/entertainment center.
Then when it is time to move, (rental) I'll remove the exterior boxes (5 screws) and conduit and restore the crappy receptacle the was originally there.