A French woman and a man of Australian national have lost their Vanuatu citizenship.
The secretary of the Citizenship Commission, Eloi Leye, says it took action after immigration officials found they were in possession of two passports.
The law of Vanuatu does not allowed dual passports.
Under Vanuatu's laws, when someone is naturalized, they surrender the passport of their country of origin.
Mr Leye says the commission had no alternative but to cancel the duo's naturalisation certificates and their passports.
Mr Leye says immigration is currently investigating a number of other naturalised Vanuatu citizens thought to have more than one passport.