Tidy catches repeated attributes, but misses identical ids!
$ cat eee.htm
<!DOCTYPE html>
<html>
<head>
<title>TEST</title>
</head>
<body>
<p id="A" id="X">aaa</p>
<p id="B">bbb</p>
<p id="B">ccc</p>
</body>
</html>
$ tidy -q eee.htm
line 7 column 2 - Warning: <p> dropping value "A" for repeated attribute "id"
<!DOCTYPE html>
<html>
<head>
<meta name="generator" content=
"HTML Tidy for HTML5 for Linux version 5.6.0">
<title>TEST</title>
</head>
<body>
<p id="X">aaa</p>
<p id="B">bbb</p>
<p id="B">ccc</p>
</body>
</html>
Not even a warning is produced.
Tidy catches repeated attributes, but misses identical ids!
Not even a warning is produced.