Dittography (from Greek διττός ‘twice’ and γράφειν ‘to write’) is the writing of a word or part of a word twice, e.g. renonown for renown. As a consequence, new material may be added to the text (cf. addition).
The opposite case, when what should be written twice is written once, is called haplography.
References
– Havet, Louis. 1911. Manuel de critique verbale appliquée aux textes latins. Paris: Hachette.
– Reynolds, Leighton Durham, and Nigel G. Wilson. 1974. Scribes and Scholars: A Guide to the Transmission of Greek and Latin Literature. 2nd ed. Oxford: Clarendon Press. || See p. 205.
– West, Martin L. 1973. Textual Criticism and Editorial Technique Applicable to Greek and Latin Texts. Stuttgart: Teubner. || See pp. 24, 133.
In other languages
DE: Dittographie
FR: dittographie
IT: dittografia