Form by reduplication:
— The consonant reduplicates after a short vowel.
— The morpheme can be reduplicated to emphasize the meaning of the word.

synonym: geminate.

Make or do or perform again.

synonyms: double, duplicate, repeat, replicate.

Roget 90: double, redouble, duplicate, reduplicate; geminate; repeat etc. 104; renew etc. 660.   

Dutch: wederhalen, herhalen, itereren, overdoen