Would additional recommendations do anything at all?

[lic]

As you may have also noticed, many schools' online app systems allow applicants to provide more than three recommendations (though optional), I am not sure if submitting additional recommendations would help me at all. Currently all my three recommenders are from my MA program, which is in polisci/IR. I did not do anything strongly related to polisci at undergraduate level (I did mostly humanties back then), but I am pretty sure that I can get decent letters from my undergrad professors who taught me in humanties disciplines. In my situation, should I submit additional letters from professors at my undergrad school? Would they be looked at by the admissions committees at all? any advice appreciated!