... dropping value "..." for repeated attribute "..."

Cause:

An attribute was used more than once in the same tag.

Solution:

Removed one of the attribute

Sample:

<img> dropping value "image.jpg" for repeated attribute "src"

BAD :  <img src="image.jpg" src="image.jpg">
GOOD:  <img src="image.jpg">


References:

HTML spec: http://www.w3.org/TR/html4/