Is there a way to prevent this?
I've investigated this; check /FORUM_FOLDER/img/smilies/smdesc.php file, open it for editing, then cut this definition:
and put it at the very end of the script before the closing );
fragment. So it looks like this:
Just to repeat: CUT IT from the original position. It should not be defined twice.
Checked it on my end and it should prevent the case you describe. Report here if it worked, I'll fix the official add-on as well then.