Regex to remove duplicate scripts from html file
<script src="js/jquery.js" type="text/javascript"></script>
    some content
<script src="js/jquery.js" type="text/javascript"></script>
    more content
<script src="js/jquery.js" type="text/javascript"></script>

<script src="js/jquery.js" type="text/javascript"></script>
    some content
    more content

(<scripts+type="text/javascript"s+src="[^"]*">s*</script>)([sS]*?)1

$1$2

<script type="text/javascript" src="javascript.js"></script>

(<scripts+type="text/javascript"s+src="([^"]*)"></script>)([sS]*?)<scripts+type="text/javascript"s+src="2"></script>

$1$3

$samp = '
<script src="js/jquery.js" type="text/javascript"></script>
<script src="js/jOOPquery.js" type="text/javascript"></script>
some content
<script type="text/javascript" src="js/jOOPquery.js"></script>
<script src="js/jquery.js" type="text/javascript"></script>
more content
<script src="js/jquery.js" type="text/javascript"></script>
<script src="js/jOOPquery.js" type="text/javascript"></script>
';

$regex =
'(?xs)
 (<script (?=s)[^>]* (?i:(?<=s)srcs*=s* "s*([^"]*?)s*") [^>]* (?<!/)>s*</scripts*>
  .*?
 )<script (?=s)[^>]* (?i:(?<=s)srcs*=s* "s*2s*") [^>]* (?<!/)>s*</scripts*>s*
';

while ($samp =~ s/$regex/$1/g) {}


print "$sampn";

<script src="js/jquery.js" type="text/javascript"></script>
<script src="js/jOOPquery.js" type="text/javascript"></script>
some content
more content