In the field validation of the table the default value function is the following:

ALLTRIM(STR(RECCOUNT()))

Is there any way two users could get the same value from this for their record?
What if these two users run code to add a record at the same time?

User1:
SELECT Table_with_default_value_for_primary_field && has 99 records
APPEND BLANK && 100th record.

User2:
SELECT Table_with_default_value_for_primary_field && has 99 or 100 records?
APPEND BLANK && 100th or 101st record?