An accidental duplication in copying or transcription in which a character, word, phrase, line, or passage from the exemplar is reproduced twice (or more) in the copy, producing an expanded or repetitive reading.

Principle

When a scribe’s eye returns to a previous point already copied, or when a marginal gloss is incorporated back into the body, motor or attentional repetition produces duplication: additional material arises from unintended reiteration of the same source segment.

Demonstration

(Illustrative scenario) Situation: A copyist writes a clause and pauses to consult a margin; the eye re‑lands on the same clause. Recognition: The scribe perceives the clause again as uncopied. Action: The clause is written a second time. Consequence: The copy contains the clause twice, creating a longer reading that later editors may identify as dittography and judge secondary to simpler witnesses.

Misapplication

Assuming every doubled sequence is a copying error. Duplication can be intentional (for emphasis, glossing, or interpolation); misidentifying deliberate repetition as dittography confuses authorial or editorial practices with mechanical error.

Consequence

Introduces expanded readings, can create syntactic awkwardness or doctrinal repetition, affects genealogical relationships among witnesses by introducing shared secondary growth, and may mislead translators or interpreters who treat the duplication as authorial.

Reversal

Not a copying error when duplication is provably authorial, paratextual (rubric, refrain), or when duplication results from a later corrector deliberately harmonizing texts; also less likely in mechanical printing processes with double impression safeguards.

Boundary

Clearly within: exact repetition of a previously copied word, phrase, or short passage in a manual transcript. Boundary case: near‑duplication where slight variation raises uncertainty (expanded ornamentation, glosses). Clearly outside: intentional refrain, later editorial insertion, or haplography (the opposite phenomenon).

Semantic Tension

Tension between textual economy (preferring the shorter, more likely original reading) and fidelity to witnesses that preserve duplications; editors balance the risk of removing possible authorial repetitions against accepting mechanical error.

Synthesis

Dittography signals additive faults in transmission rooted in attention or procedural lapses; distinguishing it from deliberate repetition or later interpolation is central to establishing a plausible text history.