Just a thought.
Based on my experience using my own uploader with multiple copies when I have multiple races.
( I do not use RSU, TFFRS or any built in ART uploaders as these are US centric. )
Could you run two copies of ART
Point the second copy at the backup location and then run your second upload from there.
You can run two copies of ART on one PC but probably best to do this on a second PC.
Ted
Keep it Simple Timing
Scotland