I am in Northeast Thailand and need to renew my US Passport, Embassy question?

I want to go to the US embassy in Laos to renew as it is close and I can avoid 2 trips to bangkok. Understand it takes 2 wks. to get the new passport, when I apply do they take my old one and keep it until the new one arrives, hoping not want to use it to come back to Thailand and then go back to pick up the new one, Thanks.