Some countries allow you to have two passports. Many do not. In the US, you must submit your old passport to receive a new one then both are returned with the old one inactivated.
Your old passport will be returned along with the new one. Usually the old one will have the sides clipped or a hold punched through it to deactivate it. Immigration can transfer the visa to the new passport
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.