This depends on how your letters are being submitted. ADEA AADSAS allows you to upload up to four letters. Some schools may even ask for individual letters separately. I used 7 strong letters. 3 of them I gave to my pre-health committee, and the additional 4 letters my pre-health advisor offered to attached to that same packet.
If you are in a situation where you can submit another strong letter, then I don’t see why you shouldn’t.