Watch the Double Dipping Arpeggios online guitar lesson by Shane Theriot from Solo Mojo

The concept of "superimposing" doesn't mean a really rude house guest that won't leave (haha), it simply means to "impose" one sound on top of another. In this example listen to what an A7 arpeggio sounds like over a Emin7 chord. The reason this works is that we are using a pattern (A7) that contains essential chord tones of the Emin7 chord, but laid out in a different way which creates a nice sound.