Whenever you update your iOS 9 to iOS 10 Beta, you do it by enrolling your device to your account you use to sign in to the beta program. So the enrollment seems like between your beta program account and profile you download for the first time, which would be Iphone beta profile as you try to update to ios 10 beta first. So next time when you try to get a watchos 3 beta profile using same account, which apparently what most of them will be using (is same iphone and same account which is obvious as watch will be connected to that phone), even though you try to download watchOS beta profile, due to prior enrollment with your iPhone to Beta Program login account, it will download ios beta profile again. if you observe closely, the profile will say ios profile, however watchos profile should say watchOs Beta Configuration profile in watch General > Setings > Profile. This is very silly bug and could easily blind side developers from Apple, as the testing suite will not simulate the device IMEI enrollment with profile. So short story to fix the issue,