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find and delete the custom header images under dashboard -> media -> library
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that is referring to header.php in the folder /wp-content/themes/twentyten/
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don’t edit wp-blog-header.php (this is a core file which should never be edited) nor header.php of your theme; simply set a ‘featured image’ for each page where you want a different header image; the image needs to have a minimum width of 940px.