- ah, they asked for all your pages, which is not usual. They must have suspected. As an FYI, you don’t have to apply via your home country’s Thai embassy. You can travel to Laos or Cambodia and apply via the Thai embassies in either of those counties.
It is fine to switch via airport, but can’t switch at landborder. I had two USA passports once and needed to switch over from one to the other (back in 2006). Tried this by exiting Laos on one and entering Thailand on the other. Immigration really didn’t like that. Was at the border for hours