Dual-frequency isn't something you can manually turn on or off, so you should just be able to run a test (I would first verify you see multiple signals with different CF but same ID in GPSTest Status view to verify you're seeing dual-frequency info). You may want to disable duty cycling for best results on Android 9 Pie or higher via developer mode - but just track whether or not duty cycling is active for each test, as it could potentially alter results.