This can happen when you swap from one mod pack to another.
When you swap you are requesting a new set of files be sent into your server directory when requesting a new mod be put into place, sometimes this leads to older mods/files being left in your server directory.
To fix this you can attempt an FTP reset by logging into your ClanForge and going to FTP
There you will see 3 boxes Restore Missing, Restore Changes & Removed Added
Leave Restore Missing ticked and proceed with the Reset FTP Changes
This should correct all the files in your server directory to only run those needed for the mod requested.
If this still fails please contact the Support Team who will investigate into this and proceed with a Mod Reset.