Anyone Make a 2-Tank Regulator that is Not Auto-Changeover?

I have a buddy who is very mechanically inclined and has owned trailers for at least 20 years. He noticed a slight propane smell from my trailer and told me the auto regulators are known to leak unless you keep both tank valves open.

We didnt discuss different brands. Was just a quick tip he told me.

Actually as im thinking back now i can remember if he said both HOSES need to be attached.....or if both tank valves need to be open.