I have dual citizenship and have both US and Philippine passports. I normally exit and enter the US on my US passport. I will be visiting Vietnam in a few months. I know US passport holders need visa but Philippine passport holders do not need visa to enter Vietnam.

I know also that the airline checks visa documentation before they issue you their boarding pass. If I show the agent that I have dual citizenship and show that I am also a Philippine citizen and do not need visa to vietnam, will this be acceptable? I usually fly on United airlines.

In line with this...is it ok to have visa stamped on my Philippine passport rather than in my US passport and show the airline agent that I have a visa for the country I will be going to?

Thanks