If title attribute == alt attribute, strip title attribute.

fix-dupe-title-alts.php

<?php

if ( preg_match_all( '/<img [^>]+>/', $post->post_content, $matches ) ) {
	$content_changed = false;
	foreach ( $matches[0] as $img ) {
		preg_match( '/title=("|\')([^"\']+)("|\') /', $img, $title_match );
		preg_match( '/alt=("|\')([^"\']+)("|\') /', $img, $alt_match );

		if ( isset($title_match[2]) && isset($alt_match[2]) && $title_match[2] == $alt_match[2] ) {
			$post->post_content = str_replace( $title_match[0], '', $post->post_content );
			$content_changed = true;
		}
	}

	if ( $content_changed ) {
		wp_update_post( $post );
	}
}