Clitic Doubling

In generative syntax, clitic doubling is an occurrence of a clitic in the presence of a corresponding (pronominal) object in a number of Romance languages.

Example
Such as Spanish:




 * Juan||me||visito||a||mi||ayer||
 * ||Juan||me||visited||(to)||me||yesterday||
 * }
 * ||Juan||me||visited||(to)||me||yesterday||
 * }
 * }

Comment
All pronominal objects, such as mi in the example, must be 'doubled' by a corresponding clitic, in this case me.

Link
Utrecht Lexicon of Linguistics