As long as said person has a citizenship in Mexico, they should be able to stay for as long as they want.
However, it may be wise to get an identification card, but it shouldn't be needed.
If you have dual citizenship, yes you can.
It allows it but does not recognize the foreign citizenship(s) of a Mexican national. This means that you should enter and leave Mexico using your Mexican passport and, while in Mexico, you are not allowed to seek consular assistance from your other country(ies) of citizenship if you get in trouble.
Hi There Currently I hold Canadian passport however I was born in Bangladesh. Do I have to have dual citizenship or I have dual citizenship?
If you are an eligible candidate for the Dual citizenship then Yes, you can have both passports.
I don't know what New Zealand thinks about dual citizenship, but I added a link to the circumstances under which Germany allows dual citizenship.
The rules of dual citizenship are quite easy to understand. Most countries neither deny or recognizes dual citizenship. However, if you are a dual citizen you must enter the country with the country's passport you own.
Yes, dual nationality doesn't stop you from getting a British Passport.
Maybe there is dual citizenship, but you need to contact passport services to find out.
You can have both passport if you are granted citisenship for both countries and if they grant dual citizenship for people.
If you have both citizenship and both their laws allow you to hold both passport then you are legally a dual citizen of the countries.
you can use a Passport/Citizenship papers
If you are a citizen of both countries then you can apply for the dual citizenship so that you can get both passports.