@Jiji **********
do you understand how the biometrics work? When the OP comes back he will need to supply fingerprints.. do you understand that the fingerprints are unique and all details relating to such finger printing checking will auto-populate on the IO's system. (also Immigration do not care how long the line is by the way).. So, if multiple 'passports' appear, of course they will take a look, and make sure it is not suspicious. Do you not think 'criminals' have tried this before? Recently some-one from UK I think it was tried to get back into Thailand after 15 years on a new passport (being a wanted person in Thai for 15 years) and got arrested! Sorry, but I disagree totally with your statement.