There are multiple reasons which can cause your embed form to show up twice or your sidebar widget to show up more than one time.
Multiple Plugins: If you have more than one of our WordPress plugins installed, it will cause the form to be fetched twice from MailMunch thus displaying the form more than one time.
Pasted Site Code: If you have the site code pasted manually AND you also have installed our WordPress plugin or Shopify app, the form will show up more than one time. Please remove the pasted code in this case.
Multiple Form Placements: By default, our WordPress plugin automatically embeds a form at the end of your posts or pages. If you plan to use a short-code or html embed code to embed the form at specific location, make sure to to turn the automatic placement off.