Manual Check Numbers

I read article 1295565.1and it led me to beleive that I could put the check number in from the check for manual payments.  My regular checks have a number range currently that started with 10001 and ended with 10102.  We entered a manual check and over wrote the system generated check number which was 10103 with the manual check number which was 589367.  On my next check run, it started numbering the checks from 589368.  How do I keep it from doing this?