Should there be two html doctype declarations on one page?

I am working migrating a clients site to xml/xs开发者_Go百科l, they have two HTML Doctypes on one page..

Is this wrong or is there a reason they may have done this?

Sections 7.1 and 7.2 of the HTML 4.01 spec speak about one HTML document type declaration:

• Section 7.1 says: "...a line containing HTML version information".
• Section 7.2 says: "...authors must include one of the following document type declarations in their documents".

See here for details.

No there shouldn't be.