About the use of two passports.

This is a question of dual nationality. Now that you have a country A passport and a country B visa, it is logical to use a country A passport to enter country B. At this time, it is hard to say whether it is acceptable to use a country C passport to enter country B. Even if it is unsuccessful, the holder can still use a country A passport to enter the country. I think it depends on the judgment of the immigration officer of country B. If you show him the passport of country A, you can enter the country smoothly. Show him the passport of country C. Although it is visa-free, there is no exit stamp of country A on the passport of country C. If the immigration officer finds this, it is a problem that needs to be explained. Another possibility is that there are many people passing through the customs and there are long queues. Immigration officials need to deal with it quickly, and I'm afraid there is no time to check their passports carefully. At this time, it is normal to enter the country smoothly with the passport of country C. Some countries recognize dual nationality, so in such countries, immigration officials will not feel anything unusual if people who have passed through customs hold passports of two countries.