When I test I seem to get both an HTML and a plain text message, is this normal?

When you send a "test" message we send you both the HTML and the plain text version separately. This is so that you can preview how both appear before you send a campaign to your contact list. When you send a campaign to your contact list only one message is sent. This message includes both the plain text and the HTML version. The version displayed to the recipient is then determined by the recipient's software and settings.