I fitted hid's and when I 1st fitted them the hid's and main beam stayed on together, the problem a rose when I dipped the main beam and the hid's didn't relight and I had no lights, I flicked the main beam back on and got stopped, but the main beam on it's own is not that good, all you have is concentrated beam but not enough light at the verge and in front of the car. As I said I never seen any car that put the dip off when the main beam was on, some suggested it might be rhe stalk in the car which has went faulty, I have a mate with a R32 I will go and see what his car does.
it's normal. If you fit HID's to the dipped beam then flick on the main beam the HID's will cool down and be extremely dim and blue when you switch back. You'll have to wait for them to warm up. If both elements came on at the same time before it was because something was wired up wrong.
If you've fitted HID's to low beam, you need to also fit a diode to trigger the relay so low stays on with high or you'll have almost no illumination (until things warm up) when switching back from high to low.
Having low stay on with high also allows you to lift your high beams more as the lows will fill in that close stuff nicely.
Of course you should look into fitting extra relays to sort out the dreadful Nissan wiring if you want your dipper switch and light switch to survive.