A student who is pursuing a BA degree while majoring in Economics can add a second major. If this second major also leads to a BA degree -- e.g., Political Science, History, Philosophy, International Studies, Mathematics (B.A.) -- then this student is only subject to the set of general education requirements that is peculiar to the BA degree.
If, however, this student were to choose a second major that leads to something other than a BA degree -- e.g., BS, BSBA. -- then this student will be subject to two non-identical sets of general education requirements. For instance, if a student were to major in Economics that leads to a BA degree, while s/he also majors in Marketing, which leads to a BSBA degree, then s/he will be subject to two sets of general education requirements, one pertaining to the BA while the other applies to the BSBA
This 'concurrent degree' track will take extra time to complete simply because of the extra set of general education requirements. If the student really desires the Marketing major in this hypothetical situation, then s/he should simply consider majoring in Economics that leads to a BSBA degree. If s/he does that, then since both Economics and Marketing lead to the BSBA degree, the student is only subject to the set of general education requirements that applies to the BSBA degree.