Around line 276 in newbb/viewtopic.php it contains:
$post_text .= "<p><br />----------------<br />". $myts->makeTareaData4Show($myts->makeTareaData4Show($eachposter->getvar('user_sig', 'N'), 0, 1, 1)."</p>";
makeTareaData4Show takes a reference to the text, therefore any changes made to it is made also to the source. Therefore, it's being processed twice.
I made the simplest change I could to make it work, and it was simply:
$sig = $eachposter->getVar('user_sig', 'N');
$post_text .= "<p><br />----------------<br />". $myts->makeTareaData4Show($sig, 0, 1, 1)."</p>";
This obviously causes it not to be processed twice because no reference is back to the original source of the variable. This fixes the bug. The core developers may have a better way as I am not super familure with the text sanatization code.
Oh, the same code appears again around line 322. I say around because I did not look at the line numbers before I started editing the code to add my own lines, sorry.
Jeremy
http://lifewithchrist.org