How to conveniently merge PDF in a large number?

Question

PDF

Given: overdose of files with tags and overdose of files with labels. You need to merge these files in pairs, preserving the name of each second. (i.e. when merging file 001 E and 001 B, the new file should be called 001B)
Files in PDF
Please help, some service or program (on macOS) to upload files in pairs and combine them with the name saved. I found many online services, but names are everywhere a problem. And I'll go crazy if I rename all the articles

Answer 1

Specifically, on this resource, when combining two files, the combined one is given the name of the first downloaded file. If we add the file file1.pdf, then file2.pdf, then the new file will be named file1-merged.pdf. In your case, you must first upload "001B.pdf", and then "001E.pdf", and the new file will be called "001B-merged.pdf"