ASP.NET AJAX JS Error - Sys.InvalidOperationException: Two components with the same id 'x' can't be added to the application.

ERROR:
Sys.InvalidOperationException: Two components with the same id 'x' can't be added to the application.

CAUSE:

ASP.NET Ajax Control Toolkit generated javascript code is in debug mode, which has extra checks that throw this error.

SOLUTION:

Set debug="false" in the web.config.

SOURCE:
http://forums.asp.net/t/1066748.aspx/1?Two+components+with+the+same+id+0+can+t+be+added+to+the+application