title: How to switch between internal and external builds on iTunes TestFlight
body: <p>I have an iOS app in iTunesConnect. Let's say with v1 in external testing and v2 in internal testing, is there a way for a user with a single device to switch back and forth between testing the internal TestFlight build and the external TestFlight build?  Can it be done with mulitple Apple ID's, one for external and one for internal testing?  I've tried this, but with no luck so far.</p>