Sales Orders - inventory allocation question

Hello,

I'm looking for documentation or tips on inventory allocation.  It seems SL doesn't always allocate inventory quantity to the first sales ordered entered.

We are using the same customer, the default priority of 5 is used with all orders.  The priority time seems to be ascending correctly in SOSched.  However, the system will release inventory to the later orders first in many cases.   Does it not process sequentially in order number range if the priority time is within the same minute?

Thanks,

Adam