You should only have one cart in your site... certainly only one on your page.
You would only need two carts if you had a registry cart or wish list cart.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.