S.,
No worries, we get these fixed. Our online store is somewhat limited: It is not aware of how many days remain on your subscription. So we manually correct these; A few times per week Patty will go through all the subscriptions that we're purchased and if there was any overlap she adds it to the end of the new subscription. Someday I may pony up the $ to customize the store to our purpose...but for now the impact it pretty minor, it only takes a few seconds per subscription to fix.
Thanks,
Walter