Texting problems on Lumia 1520 with Windows 8.1

I bought 2 new Lumia 1520's in an AT&T store with 8.1 preloaded. One for me & one for my wife. My phone was activated by the salesman in the store. My wife's phone was activated about a week later when I got home. Her phone was activated in a different AT&T store. Now we are having texting problems. Her phone and my phone receives every text that is sent to her by her friends & co-workers. She also receives every text that is sent to me by my friends & co-workers. When I send her a text, she receives it and it also comes back to my phone. This is very annoying. How can this be fixed? Group text is turned off. Both phones have the same SMS center number. Is this how it should be setup?