You can keep your old passport, but once you get a new one and the old one is presented uoon renewing your passport - they punch holes in it. At least they did mine. CA got her passport in 2018, and traveled to Europe that summer. Her passport doesn’t expire until 2028.
Do we know when KA's passport was last issued and expires? From the Inside Edition video interview with the person who had the two passports in his hand in Costa Rica that he found in KA's locker after she was apprehended, it looks like KA's passport expired in May of 2021, but it is hard to read as it is blurry and it's a video, not a still picture. Does anyone know?