Hi Luc,

SYS(2015) is completely based on date and time and it uses only part from the date. It is guaranteed to be unique within the same process if it doesn't run more than a century. Given that, there is a possibility to get the same value within another process or after a century.
The fact that calling the function in a loop for some time doesn't produce duplicate can not be taken as a proof.

Thanks,
Aleksey Tsingauz.