Hi I need some help here. I have 2 passports(duo nationalities). I entered Bangkok with passport A

You need to use your passport A for application Chinese tourist L type.
During the application, they do need the passport A with your entry stamp for Thailand as a proof of your legal status in Thailand, otherwise, you are not able to apply for a Chinese L.

Thank you Eden for your reply. Now the question is, if I give my passport A to the embassy for china application, can I take the flight from Bangkok to Krabi with my passport B, which has no entry stamp? Or can the embassy give me a proof that my passport A is being using for application that can be used with domestic travelling with planes?

Many thanks.
Wil

Without a entry stamp, you may not you Passport A to take a flight from Bangkok to Krabi, but I am not very sure about the requirements in Thailand. Maybe you need to consult the airline company for more detail information.

The Chinese embassy will give you a proof to show that your passport is using for application and maybe you can use it for traveling.

Since the application processing days are around 4 working days, you may try to avoid using your passport A during these days if possible.

Hi just want to update what happened. I entered Thailand with passport A so I gave the China embassy my passport A(with entry stamp) for China visa application. During the waiting period, I took domestic flight from Bangkok to Krabi with my passport B, without entry stamp, no problem and no question asked : )