Assemble without duplicate

[r.zegwaard]

Hi,

I need to assemble 2 jobs in a folder based on jobname and/or metadata.
Jobs are named like this File_<number>-Part<code>.pdf
File_1234-PartA.pdf
File_1234-PartB.pdf
File_5678-PartA.pdf
File_5678-PartB.pdf

As the job-identifier, I want to use the number in the filename. Sofar it's quite easy.
But... the part code must be unique.
So, if 2 jobs with exactly the same name arrive, they should not be assembled.

Any suggestions?

Robert