<p>Economics + IR is a double major (within a single school), not a dual degree (between two schools). </p>
<p>In your case, I think it can probably be done without adding any extra classes to the number of credits required to graduate with a single major. Likewise, two concentrations in Wharton or two SEAS majors can be done without adding extra courses.</p>
<p>The difference is that you’ll be using your elective spots to fulfill requirment for another major, so you’ll have fewer true electives.</p>
<p>For dual degrees, The most demanding combination is Wharton + SEAS, which requires 4-6 more classes than the normal SEAS requirement, which amounts to about 4.5 years (with no AP credit and no overload semesters). Wharton + CAS can be done cleanly in 4 years with no AP and no overloads.</p>