Are your categories being duplicated by an import tool? Categories should only be created by the import tools if they do not already exist in your store. If you are finding that your import tool is creating categories that already exist, you should check the following:
- The category name in your CSV/XML file matches the category name in your store exactly.
- There are no extra spaces before or after your category names in your CSV/XML file.
- The category name in your CSV/XML file uses the same case (upper or lowercase) as the category name in your store.
- If you are using a category delimiter, make sure there are either no spaces either side of the delimiter, or you specify the spaces as part of the delimiter in the category delimiter field. Otherwise splitting the categories by removing the delimiter will leave rogue spaces in your category names.