Can I submit more than one letter of recommendation for first-year USC?

[this is more of a specific college admissions question, but I figured I’d post on this sub as well in case anyone here has insight]

Submitted my application for USC last month, but I still have yet to send my letter of recommendation.

Currently, I have one reccomendation from a high school teacher and a second from my private music instructor. On the Commonapp, it states “1 Optional” for teacher evaluations and “Not Applicable” for other evaluations. What does this mean exactly? Will admissions be annoyed if I send more than one reccomendation (one of which being an “other” reccomendation?) Is it worth a shot to send my teacher recommendation in through Naviance and then just have my music instructor email her letter to the school? I would like to submit both recommendations if possible but just wasn’t sure how rigid the guidelines on the commonapp are.