I Recently purchased 2 ringtones from itunes. When I sync them there is two copies of the same ringtone and the other one is missing. The same thing happens when I tried to make ringtones with Garage Band?! Any Suggestions?! Thanks.
Do you have the box "manually manage music" checked on the iPhone? This is a bug in doing ringtones. You need to uncheck that box, and then sync with iTunes. Make sure that you have your music either in a playlist or something else so you can sync it back to the iPhone. Once you get the ringtone on there, you can check the box again.
I would try to set iTunes NOT to sync the ringtones and see if that removes them from the phone. Then, after changing the manually manage music checkmark, recheck to sync the ringtones and see if that helps.
I haven't bought a ringtone but I've made a few in garageband and exported to iTunes. To first get them onto the iPhone I had to reset the phone deleting all I had on it and start again having the ringtones as part of the initial sync. However, when I made another one and tried to have it sync it wouldn't (I also had that multiple single ringtone issue).
What I did is a workaround more than an answer: I simply dragged the ringtone from the list onto the iPhone icon under devices and it was added and works. I still can't get it to sync the ones I want but dragging and dropping seems to work. Try it yourselves and let me know if it works for you.