That's cause by assetcraft plugin. http://assetgateway.com/minecraft/hosting-plans/ Assuming that's skitscapes server
/who ohh just had an idea not sure if it exist when someone types /who a it displays peoples names which starts on a EDIT by Moderator: merged posts, please use the edit button instead of double posting.
Remember to set the server properties to the wished amount of spaces u want (some servers do this automatic, others don't)