Classical measures against double vote imply the control of the identity documents of the voter at the polling station. In order to make the right to vote effective, a number of countries recognise several documents as valid – for example, an identity card or a passport, since a number of people have only one of them. They may even admit that the same person holds two passports. Moreover, the validity of some documents can be unlimited or the use of expired documents be admitted: recognising voters through their photo is therefore not always easy. This makes the identity control insufficient to prevent fraud in case the electoral lists are not fully reliable. Identity control is a full guarantee against impersonation only if each voter is provided with a specific document, as is the case in Mexico or in the Dominican Republic. Fraud is made more difficult if supplementary measures are taken against the falsification of identity documents, for example by the use of biometrical data, or if two identity documents are requested (Argentina).