Post: Consider the following pasuk in Korach (Bemidbar 17:25), together with its trup. The pasuk:
|כה וַיֹּאמֶר ה אֶל-מֹשֶׁה, הָשֵׁב אֶת-מַטֵּה אַהֲרֹן לִפְנֵי הָעֵדוּת, לְמִשְׁמֶרֶת לְאוֹת, לִבְנֵי-מֶרִי; וּתְכַל תְּלוּנֹּתָם מֵעָלַי, וְלֹא יָמֻתוּ.||25 And the LORD said unto Moses: 'Put back the rod of Aaron before the testimony, to be kept there, for a token against the rebellious children; that there may be made an end of their murmurings against Me, that they die not.'|
And the trup:
Note the words lemishmeret leot livnei-meri. The words lemishmeret leot are joined together*, and is separated from livnei-meri. Thus: lemishmeret leot || livnei-meri.
Shadal writes about this:
"I found in a manuscript on parchment... [the trup as depicted above]... and it is correct."
That is, a tipcha on limishmeret and a mahpach on leot. The word lemishmeret is separate and leot livnei-meri are joined together**. Thus: lemishmeret || leot livnei-meri.
I can understand the impulse to promote this variant text, as it seems to work better with the logic of the pasuk. It is a mishmeret and it is an ot livnei meri. Or it is a mishmeret livnei meri and a ot livnei meri. But it is not a mishmeret leot.
Still, the mahpach on the word before the etnachta seems more than a bit strange to me. And perhaps the clustering of these two prepositions is understandable based on Wickes' syntactic dichotomy. That is, Wickes writes that in general, a prepositional phrase (such as "for a mishmeret") or adverbial expression at the beginning of a clause is separated off by itself. However, there are exceptions. And among the exceptions, he writes:
Maybe these form a similar cluster at the head of the clause.
* since mercha on lemishmeret is a joining trup, and tipcha on leot is a separating trup.
** since tipcha on lemishmeret is a separating trup, and mahpach on leot is a joining trup.