When attempting to send an Approved Email Online, the Approved Email page is displaying two copies of the Subject line:
The HTML for the Approved Document has two or more <html> tags within the same document. This creates an invalid HTML document resulting in the Online Approved Email page being unable to correctly parse the HTML.
Ensure that the Approved Document HTML only has one <html> tag and validate that the HTML adheres to HTML standards.
CRM Help Documentation: Approved Email Templates