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.
Yes, Thailand allows dual citizenship.
Israel allows dual citizenship for those who immigrate to Israel based on Law of Return (aliyah): you have to be Jewish to qualify to hold dual citizenship in Israel.
yes.the new constitution allows one to have dual citizenship
The British government allows dual citizenship. However, the government of the other country might not allow this thus force you to renounce British citizenship if you want to become a citizen of their country.
Yes, El Salvador allows dual citizenship. Just renew your Salvadoran passport, if you haven't, and you are good to go.
ISRAEL.
Well, Peru itself allows dual citizenship. But each case depends on where you are from. Your native country may not allow you to hold your nationality after you become a citizen of another country.
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 US recognizes dual citizenship.
India does not allow dual citizenship.
Dual citizenship is when one has citizenship rights in two countries.
You can get dual citizenship for the Philippines if you are a natural-born Filipino who has become a naturalized citizen of another country, and to retain your Philippine citizenship, you have to take an oath of allegiance to the Republic of the Philippines before a Philippine Consular Officer.