I have valid US and Ecuadorian passports due to birth in Ecuador and being naturalized in the US. I plan on traveling to Shenzhen via Hong Kong. Basically my flights are to/from Hong Kong and I will take a train to the Futian Border Crossing (福田口岸) and cross to/from Shenzhen.
Is it OK to apply for a Chinese L-Visa on my Ecuadorian passport instead of my US passport?
When traveling to HK/Mainland China, is the following sequence OK?:
Show US passport
Show Ecuadorian passport with Chinese L-visa
Show US passport
I don't know much about the metro border control and if it works like airport border control - all I know is it exists.