DCT4 Calculator 2.2 S/W

I bought 2 Nokia 6610 phones from T-Mobile (USA). I requested and got the
unlock codes from T-Mobile for these two phones. I tried to test out the
DCT4 Calculator 2.2 S/W to see if the unlock codes generated by this S/W are
same. I used the DCT4FREE and run command as follows:

DCT4FREE 2 123456789012345 31020 32820

where 123456789012345 is my IMEI, 31020 is provider code,
and 32820 is Box Serial code. The code generated (line #1) by DCT4 S/W was 1
digit different with the unlock code I got from T-MOBILE. The code I got
from T-Mobile is 31735xxxxxxxxxx and the code generated by DCT4 S/W is
31730xxxxxxxxxx (0 instead of 5) ? I tried the second IMEI and got
05427xxxxxxxxxx instead of 05422xxxxxxxxxx (from T-Mobile) ??? I played
around with the Box Serial codes. Running with same command with Box Serial
code 32825, I got both codes matched with codes I got from T-Mobile.!!!

Is Box serial code 32825 correct? How do I know which Box serial code to
use?

Thank you,
Anh Ho