ID %1 already defined

Cause:

An "id" is a unique identifier. Each time this attribute is used in a document it must have a different value. If you are using this attribute as a hook for style sheets it may be more appropriate to use classes (which group elements) than id (which are used to identify exactly one element).

Example:

textexample textexample

Bad:
textexample
textexample
Good:
textexample textexample

Solution:

textexample textexample

References: