You can list items in 2 store categories, you could have size categories as well type of item, blouses, skirts, dresses etc

You can add or edit categories using Bulk Edit.

Go to your Selling section and either select all or select a group of items that you want to place in the same category.

Click the Edit button at the top.

If you selected All, now select a group of items that you want to place in the same category.

Under the Edit Fields drop down at the top, select Categories.

Next to Store Category select Change to and then find the correct Category.

Repeat for the second Category.

Save