Note: the Product Template for this item must be set to “Variants in Grid” in order to display both variants. This is set on Catalog->Products->Manage Products. Edit your product and find the Product Template drop-down.Typically, most products will have only a single product variant. And even in cases where there may be multiple sizes or colors, leading you to believe you need a variant for each of these combinations, you will find another option called Product Variant Attributes will be your best answer.
Create a product with a single variant (Example: Keychain with logo)
Create a product with a single variant but with multiple product variant attributes (Example: Shirt with multiple colors and sizes)
Create a product with multiple variants (Example: Book with both soft and hard cover options)
Offer a downloadable product (Example: Organization Mailing labels)