is there a way to over right songs in the library? 

If you're uploading the file through the web interface, the old file should simply get overwritten by a new file with the same name.

However, if you're using a FTP software, you'll likely need to modify some settings, as many FTP software will not overwrite files and will simply rename the new file.

thanx alex
yes im using the web interface but when I add..its adding the same song twice??
so theres the new one and the old one...im missing something....?

If you overwrite a file with another of the same properties and name, then no, a second item should not be added to the media library, either the old item will be removed, and a new one added, or if the id3 tag is also identical, then Centova Cast might not detect any changes, in which case it will continue using the same old entry in the media library for the new file.

HTH

yea,all I did was edit the audio,all tags are the same..is there a step by step somewhere I can read?.. maybe im just not putting it in the right place..will it call out to over right?....thanx roger