iPhone Ringtones Problem...!!!Plz Help

Recently, I hv experienced an issue.
Actually, it has been mentioned by other BROs before,
Anyway, when I created my second ringtone and tried to input it into my iphone, the problem come(only in the iphone but not affect in my i-tune's ringtone section in my MBP), the newly inserted file had overwritten the first ringtone file, including both the file name and the ringtone, so how to solve it?