I am wondering if it is possible for me to launch 2 versions of my app. So that users downloading it would have a 50% chance of getting one or another version.
For example, one would have one sort of camera and the other would have another kind (To compare the performance of app with one of the two cam layouts)
Simple: compile your app with one bundle id, let's say com.author.app1, change bundle id in the project settings to com.author.app2 and compile again. You will will get two apps with the same name on your device. You can make two targets that will differ by the bundle id.
If you want to distibute your app (AdHoc. Not via App Store), you may have few Apple accounts.