No way anybody here can do anything without even the actual error nor the code/script/function to look at to see if could possibly spot something...
That symptom would tend to imply a logic error that the code did try to create a second copy of the same dataset under some circumstance, but all we can do is hypothosize...
If you can reproduce the symptom, it should be possible to track down the cause; if it is intermittent, it would be tougher...