Same problem on a Sprint phone
My wife and I have two new Sprint 4S phones. They worked perfectly until the upgrade. The phones are a week old. The Apple ID is the same on both. The phone numbers and gmail accounts associated with them are different. My messages from her now come in from the email associated with the Apple Id. Mine to her come now as my cell phone number on caller ID and messaging. While we we experimenting with setting changes to correct this a third texter popped in and showed as messages from us. There is a change caused by the upgrade and a security breach.
My wife and I have two new Sprint 4S phones. They worked perfectly until the upgrade. The phones are a week old. The Apple ID is the same on both. The phone numbers and gmail accounts associated with them are different. My messages from her now come in from the email associated with the Apple Id. Mine to her come now as my cell phone number on caller ID and messaging. While we we experimenting with setting changes to correct this a third texter popped in and showed as messages from us. There is a change caused by the upgrade and a security breach.