Multiple DNT Headers (ACTION-283, ISSUE-150)

Proposed text on duplicate headers:

If a server receives duplicate DNT headers, it MUST act as if it had received a single DNT header.

Proposed text on conflicting headers:

If a server receives conflicting DNT headers, it MUST act as if it had received a single DNT: 1 header. It is a best practice for the server to alert the user about possible user agent misconfiguration.