Will my cousin face any immigration issues traveling to Thailand on a Portuguese passport after previously visiting with an Indian passport?

A user inquires about potential immigration issues for their cousin, who previously traveled to Thailand on an Indian passport and now has approval for a Portuguese passport. A commenter notes that dual passports are common and that Thai immigration will use biometric data to link the two passports. If the individual is a regular tourist and not trying to misuse the dual passport system, there should not be any issues during immigration.