Penn is very flexible in terms of double majoring. It would probably require an immense amount of work and a pretty substantial drop in the engineering GPA to be able to produce good architecture work though.
I don't know anyone who has gotten a dual degree with engineering. However, I do know many who have gotten an undergraduate degree from Wharton and architecture. It really did put a heavy strain on them though, and they couldn't devote the time they wanted to the architecture projects.
Here is the link for the undergraduate program at Penn:
http://www.design.upenn.edu/new/arch...rad/index.html