This is an accepted solution.
Short answer - yes, open a second Shopify account. You can't easily run two different stores off one Shopify account, so simplest is two Shopify accounts.
Yes, you have to create a second Shopify subscription, but you can do it from the same login/email address, so once you're logged in to the admin portal you can easily switch between the two. The two stores are compltely seperate. When I did this, as a starting point I exported the theme from one store and imported it into the other - that way all my settings and custom code editing were carried over (but not any products etc).