You can have as many HTML Web Signup forms on a webpage as you want. In order to have multiple HTML forms:
Browse to the Form and Email Design Wizard by selecting the Web Signup Forms Option from the Lists Menu.
Select the Create HTML Embed Form from the Resources Dropdown.
Now you can design and modify the form as you see fit.
Once you're done, copy the code in the Copy/Paste code to your site section and paste it into your website.
This will create a single signup form.