OE - use R083800 to stop/start the same DBA with a different (new) rates

For those employees who are keeping the same plan(s) as previous year, they do not need to go thru OE link.  We simply run R083800 program to update the rates if different from the previous year.  I put the new rates in plan master > plan rates and ran R083800 to see the resukts.  I noticed that it stopped the plan with old rates effectived 09/14/2018 and started the same plan with new rates effective 09/15/2018.  This is good as expected.  However, the plan with the new rates with effective date 09/15/2018 also ended/stopped effective 09/15/2018.  And I don't understand