Why are some of my Variation Attributes duplicated?
This may occur if there are slight differences in spelling or encoding differences between your Variation Attributes. Variation Properties of Small, Medium and Large, the other has attributes of Sml, Med, Lrg. When the Listings are merged together under the one Product, both size properties will be displayed for the Product.
To merge together duplicate variation attributes, please follow the instructions in this help article: How do I merge together Variation Attributes?