Dear Eman,
Thanks for your post!
The answer to your question is that in most cases you should only submit the number of letters that the school requests. Submitting more creates additional work for your admissions reader - and in some cases additional exasperation - so you need to be absolutely certain that an additional letter would truly add value to your candidacy.
In order to asses your specific case, I would need to know more about your overall profile and the profiles of your potential recommenders.
For more information on this topic, you may want to read Clear Admit's blog entry on selecting recommenders:
https://blog.clearadmit.com/2009/06/admi ... menders-3/
You might also want to read Clear Admit's Recommendation Guide, a downloadable PDF title in our popular Strategy Series:
https://www.clearadmit.com/ss_reco
Best of luck,
Graham
