When you are adding accounts, it will give you the option of adding existing accounts (which you have used previously), as well as the option of adding new accounts. Existing accounts will be checked by default, and adding brand new accounts will be unchecked by default. If you simply clicked on add without changing the check boxes, then you will have added your previously used account(s) and not added any brand new accounts, which it sounds like is what you are trying to achieve.
You can confirm this is correct by ensuring your balance is accurate and that all your coins are accounted for.