@Bonta ****
You are correct. If you move away and get a foreign passport then your thai one is forfeit. Try coming to thailand using you thai passport then leave using you other because you have no visa on your thai passport. The immigration will take your thai passport off you. Yes you can have a thailand passport again but you must forfeit your second nationality first. Just make sure you do not own land inbetween as I will become messiy as it was owned illegally as a foreigner.