Here is a PDF of what a Jerome Fisher BSE/BSE program looks like:
http://www.upenn.edu/fisher/curriculum/sample2.pdf
In regards to what courses/requirements can be double-counted, how this type of curriculum varies with your engineering major, weather you are double concentrating with Wharton (which is possible, but difficult i presume), I have no idea how many total units this would be.
Here are some pertinent quotes from the M&T website: "The majority of M&T students complete the program in four years...The majority of M&T students take five to six courses per term".
Are there any M&T or SEAS/Wharton dual majors out there who can elaborate on the length of study required?