fdupes | fdupes is a program for identifying duplicate files | File Utils library

I have two directories - A and B - that contain a bunch of photo files. Directory A is where I keep photos long-term, and the files inside are sequentially named "Photo-1.jpg, Photo-2.jpg, etc.".

Directory B is where I upload new photos to from my camera, and the naming convention is whatever the camera names the file. I figured out how to run some operations on Directory B to ensure everything is in .jpg format as needed (imagemagik convert), remove duplicate files (fdupes), etc.

My goal now is to move the files from B to A, and end up with the newly-added files in A sequentially named according to A's naming convention described above.

I know how to move the files into A, and then to batch rename everything in A after the new files have been added (which would theoretically occur every night), but I'm guessing there must be a more efficient way of moving the files from B to A without re-naming all 20,000+ photos every night, just because a few new files were added.

I guess my question is two parts - 1) I found a solution that works (us mv to rename all photos every night), is there any downside to this? and 2) If there is a downside and a more elegant method exists, can anyone help with a script that would look at whatever the highest number that exists in A, then re-name the files, appending onto that number, in B as they are moved over to A?

Thank you!