Mercha kefula (Hebrew: מֵרְכָא כְּפוּלָה, with variant English spellings) is a rare cantillation mark that occurs 5 times in the Torah (once in Genesis, once in Exodus, once in Leviticus, and twice in Numbers) and once in the Haftarah (for Behaalotecha and for the intermediate Shabbat for Chanukah, in the Book of Zechariah.)
Dr. David Weisberg suggested[1] that the merkha kefula mark is found on words that refer to an aggadic tale.
For instance, he claimed[1] that the merkha kefula of Zechariah 3:2 is meant to remind the reader of the aggadic legend that the high priest Joshua was literally thrown into a furnace (as recorded in the Talmud, b. Sanhedrin 93a).
The Merkha kefula mark appears in the following locations in the Torah: It also occurs in the Haftarah at Zechariah 3:2, read on the (first, if there are two) Shabbat for Chanukah and for Parashat Behaalotecha.
The Merkha kefulah note occurs a total of 14 times according to the Leningrad Codex.