Hi everyone!
I am using Interfolio to distribute my letters of recommendation but I’m not sure if I can use the same letters for AMCAS and AACOMAS. I noticed that AMCAS has a letter ID for each author and wants that letter ID on each letter so they can match it with their application. Does that mean that I have to ask my recommenders to upload two letters, one with the AMCAS letter ID and one without it for AACOMAS?
Any input will be greatly appreciated! 
If I remember correctly, you get to enter all the IDs that are relevant. So your interfolio file will contain many different IDs. I had TDMSAS and AAMC IDs. Respective entities will be able to map your corresponding IDs to your file.
I don’t remember exactly how that works, but I remember it was a fairly easy and smooth process and at no time had I asked my references to worry about those IDs.