ANDROID_ID after factory reset

Question

According to the google documents about ANDROID_ID, its value is unique until factory reset has done. I have a question about new generated ANDROID_ID after factory reset .

Is this value unique as old value? Is it possible that the new value is not unique?

Answer 1

According to this:

However, the value may change if a factory reset is performed on the device. There is also a known bug with a popular handset from a manufacturer where every instance have the same ANDROID_ID. Clearly, the solution is not 100% reliable.