Number One: Allow you to invest or bank abroad when many financial institutions will not accept you as a citizen from a particular country (US Citizens Take Note)..
Number Two: Possibly save your life when the country that has issued your first passport is at war or has engaged in some activity to make you unwelcome in certain places.
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Number Three: Offer an existing option should you decide down the road to renounce citizenship from country number one for whatever reasons, including increased taxation.
