The challenge in showcasing Eric E. is that he does such a huge variety of styles, that you can't listen to one or two and think you have him figured out. He does gorgeous acoustic ballads, high-energy rock and blues, sensitive jazz, etc. etc. On these demo tunes, when you hear harmony, and two guitars at once-- Eric actually does this live by use of loops and a harmonizer effect. This is how he sounds live.
Here are a few examples, audio & video:
Horrible production, but showcases Eric's improvisational skills on a high-energy blues