You can install DVD Profiler on multiple iOS devices as long as the same Apple ID is used. If your wife has a separate Apple ID, she will need to buy the app again.

To sync the databases on both of your iPhones, you will need DVD Profiler for Windows. There is no need to purchase it, the free version will do. You can sync your phones with the desktop program. Just make sure not to sync both phones at the same time.