gemination (rhetoric)
Definition - The immediate repetition of a word or a phrase for rhetorical effect.

Example -
See the OED citation below for a good example.

Etymology -
The term derives from the Latin geminare, to double.

Oxford English Dictionary -
Its first citation is from 1650:
"First putting forth his hand, My God; yea both his hands, My God, my God, claiming by that gemination a double interest in Gods fatherly affection."
(Fuller Pisgah iii. xii. 345)

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