I'm with Passmark as I'm confused what you've imaged and what you are looking at. Can you please clarify…
Do you have 10 USB devices that you have imaged that you have been told should be the same but the MD5 does not match?
Or have you taken 10 images of a single USB drive and the MD5 hashes of the images do not match?
The first could be due to the data not being the same despite you being told it was…
The second could be more serious as something has gone wrong in the imaging process
I don't think the which batch a chip came from is important. The only issue is the number of sectors on the chip. A different number of sectors would explain different hash value, same number of sectors, with ANY chip, should result in the same hash value.
I am very interested in this discussion but have some questions first.
1. What are "flash cards". Are these normal flash drives as in USB thumb drives or are they something else? A card implies one that installs into a slot inside a computer or a PCI Card for a laptop.
2. If these are USB Flash Drives are all ten of them the same brand and model or are they different?
3. Are they all the same size?
4. If not the same how many different models and sizes area there?
5. Were they all bought from the same source at the same time?
6. Is this for a case or is this a test?