Yes, you are allowed to create multiple storefronts, however you will need to register them as separate accounts, under different URLs and email addresses.
Many times designers want to create multiple storefronts for the purposes of uploading different content niches and art styles. However we actually recommend you take advantage of integrating albums instead, keeping all designs in one storefront. Why? Because generating more traffic to one storefront, instead of spreading that traffic across multiple, can help improve your Google search ranking!