What is the reason that stand behind the fact that the rarest musical notes (Teamim) in the Torah are located in the same verse? What is so special in this specific verse to be chosen for those special Teamim? In addition, what is the reason for the location of so many of them in the same verse? The special Teamim in the Torah are located in (Parashat) Matot sidra (Bamidbar - Book of Numbers, 35:5): וּמַדֹּתֶ֞ם מִח֣וּץ לָעִ֗יר אֶת־פְּאַת־קֵ֣דְמָה אַלְפַּ֪יִם בָּֽאַמָּ֟ה וְאֶת־פְּאַת־נֶ֩גֶב֩ אַלְפַּ֨יִם בָּאַמָּ֜ה וְאֶת־פְּאַת־יָ֣ם ׀ אַלְפַּ֣יִם בָּֽאַמָּ֗ה וְאֵ֨ת פְּאַ֥ת צָפ֛וֹן אַלְפַּ֥יִם בָּאַמָּ֖ה וְהָעִ֣יר בַּתָּ֑וֶךְ זֶ֚ה יִהְיֶ֣ה לָהֶ֔ם מִגְרְשֵׁ֖י הֶעָרִֽים׃ AS can be seen above, the rarest Teamim in the verse are Karnei Para, Yerach Ben Yomo and Mercha Kefula?
As Joel mentioned, there is no mercha chefulah in the verse. The "reason" for the other two, is that one of the yerach ben yomo and karnei farah necessitates the other, since the yerach ben yomo is the trop which was designed to lead into the karnei farah (similar to the relationship between a zarka and a segol). This relationship appears every time these trop are used across the rest of nach as well.
See also the Wikipedia article linked in this answer, which explains when this grouping is used according to grammar rules.