Problem with override

Here is a strange one.

I have to work on a file through two different names. One is the physical file, 
the other is a name that is overridden to the same physical file:

Contract        Physical File (Input)
Contractb       Override to the Physical File Contract (Update)

The agent numbers in order on the file are:
027685
027697
027697

When the program code is:

Loop

        Read Contract file

        If Agent # changes
                Chain to ContractB file using keys saved in previous read of 
Contract File
                No Update necessary
        endif

        Save keys for Contract Record

endloop

The CL program does this:

        OVRDBF CONTRACTB CONTRACT

If this override didn't take, then the program couldn't run. CONTRACTB doesn't 
exist.

The order the program reads the record
...
027685  20060326
027697  20060325
027685  20060326
027697  20060327
...

Can anyone tell me why it rereads the 027685 out of order. The 027697 are both 
different.

My work around involved inserting a chain to the CONTRACT file to reread the 
027697 record to ensure that I was still on that record.

Does CONTRACTB still have the same open file data path as CONTRACT even though 
they are opened under different names?

I'm stymied.

Marvin