Program for Exchange Gets Contacts with Duplicated "OrganizationalIDNumber"

We have an old VB program that copies contacts from Microsoft Exchange to our SQL database.  This worked fine for many years until 2017 when it started getting duplicated OrganizationalIDNumber from new contacts.  I have been manually worked around this problem ever since (because I was busy and I am not familiar with this VB program).  Now that I get some time, I want to fix this problem for good.

We are expecting the OrganizationalIDNumber to be "1", "2", "3", ....  But the new contacts all get the same ID "4303".

I am under the impression that OrganizationalIDNumber is 32-bit.  This should represent a very large number.  Moreover, the program is using it as a string, and it is saved in our database as a varchar(255) data field.  The ID should not be truncated (or so I thought).  This certainly appears like the ID is being truncated though.

My questions are:

1. Does this look like something that you have come across?  What is the solution?
2. Where is the configuration setting in Microsoft Exchange that defines the data type of OrganizationalIDNumber?

Our Exchange is version 2016.

Please help if you can.  Thanks.

jchan