I'm having the same issue on only one of my two iPods ?!
I have the following:
iphone 4S - OS 6.1.1
ipod Touch # 1 - OS 6.1.2
ipod Touch #2 - OS 6.0.1
All three devices have unique e-mails registered. Touch #1 has the iphone number i don't want.
If I log out of my apple id on the iphone and reset network settings on Touch # 1, then the number is gone. As soon as I log into AppleID on the iphone, the number re-appears on Touch # 1. Argh.
This does not happen on Touch # 2 which makes me think there should be a solution other than separate Apple ID's.
Any help is appreciated.
TIA