My client asked me to check if duplicate serial numbers for the same product is possible. I originally said "of course not, don't worry", but then promised to check it. The validation checks on a 2nd receipt with the same serial number does indeed give the required error message, but if the receipt is into a DIFFERENT warehouse to the existing item, then it lets me do it. 

I couldn't find any posts on this, can anyone confirm if there is a valid use case for allowing duplicates? Or else I'll raise it with support.

Thanks

Alex