allow simultaneous multiple computers to fulfill sales orders

how can we set up NetSuite to allow simultaneous multiple computers to fulfill sales order?

When you try to fulfill at the same time, one order goes through and one order gets flagged:

If you're batch fulfilling, and there are several orders in a row attempting to fulfill, you will have to stop at every one as it tries to give it the same number.

Steps we took:

We both created a fake sales order

We both clicked "fulfill" at the same time (counting down from 3)

We both clicked "save" at the same time (counting down from 3)

1st computer finished processing first, and she got the original number. But since they both started at the same time, they were (presumably) assigned the same number at the start. Hence, mine was flagged as a duplicate.