The Mishnah on Sotah 40b reads:
מַתְנִי׳ בִּרְכוֹת כֹּהֵן גָּדוֹל כֵּיצַד? חַזַּן הַכְּנֶסֶת נוֹטֵל סֵפֶר תּוֹרָה וְנוֹתְנָהּ לוֹ לְרֹאשׁ הַכְּנֶסֶת, וְרֹאשׁ הַכְּנֶסֶת נוֹתְנָהּ לַסְּגָן, וְהַסְּגָן נוֹתְנָהּ לְכֹהֵן גָּדוֹל,
MISHNA: How are the blessings of the High Priest recited on Yom Kippur? The synagogue attendant takes a Torah scroll and gives it to the head of the synagogue that stands on the Temple Mount, and the head of the synagogue gives it to the deputy High Priest, and the deputy High Priest gives it to the High Priest.
וְכֹהֵן גָּדוֹל עוֹמֵד וּמְקַבֵּל, וְקוֹרֵא ״אַחֲרֵי מוֹת״, וְ״אַךְ בֶּעָשׂוֹר״. וְגוֹלֵל אֶת הַתּוֹרָה וּמַנִּיחָהּ בְּחֵיקוֹ, וְאוֹמֵר: יָתֵר מִמַּה שֶּׁקָּרִיתִי לִפְנֵיכֶם כָּתוּב כָּאן. ״וּבֶעָשׂוֹר״ שֶׁבְּחוֹמֶשׁ הַפְּקוּדִים קוֹרֵא עַל פֶּה.
And the High Priest stands; and receives the Torah scroll; and reads the Torah portion beginning with the verse: “After the death” (Leviticus 16:1–34), and the portion beginning with the verse: “But on the tenth” (Leviticus 23:26–32); and furls the Torah scroll; and places it on his bosom; and says: More than what I have read before you is written here. He then reads by heart the portion beginning with: “And on the tenth,” from the book of Numbers (see 29:7–11).
While our text has כֹהֵן גָּדוֹל עוֹמֵד וּמְקַבֵּל, וְקוֹרֵא ״אַחֲרֵי מוֹת״, a variation has an addition omed: כֹהֵן גָּדוֹל עוֹמֵד וּמְקַבֵּל, עוֹמֵד וְקוֹרֵא ״אַחֲרֵי מוֹת״.
Thus, the Mishnah in Yerushalmi Sotah:
בִּרְכוֹת כֹּהֵן גָּדוֹל כֵּיצַד. חַזָּן הַכְּנֶסֶת נוֹטֵל סֶפֶר הַתּוֹרָה וְנוֹתְנוֹ לְרֹאשׁ הַכְּנֶסֶת וְרֹאשׁ הַכְּנֶסֶת נוֹתְנוֹ לַסְּגָן וְהַסְּגָן נוֹתְנוֹ לַכֹּהֵן הַגָּדוֹל. וְכֹהֵן גָּדוֹל עוֹמֵד וּמְקַבֵּל עוֹמֵד וְקוֹרֵא אַחֲרֵי מוֹת וְאַךְ בֶּעָשׂוֹר. וְגוֹלֵל אֶת הַתּוֹרָה וּמַנִּיחָהּ בְּחֵיקוֹ וְאוֹמֵר יוֹתֵר מִמַּה שֶׁקָּרִיתִי לִפְנֵיכֶם כָּתוּב כָּאן.
Similar text appears in Ktav Yad Kaufmann, Sotah 7:9:
Munich 95 has it while Vatican 110 does not.
Others with the additional omed:
The NLI: 4° 577.4.34 Talmudic fragment likely has it. Even though the word was obliterated, given the amount of space, I would guess that there is enough for both the phrase וקורא אחרי as well as עומד until the end of the line.
Why should there be a repetition of the word omed? Isn’t he already standing? You need to see to contrast with the following Mishnah, for the parashat hamelech. The king receives it while standing but then reads it while sitting.
By the way, this contrast also provides an alternative explanation to the question that the gemara poses.
וְכֹהֵן גָּדוֹל עוֹמֵד וּמְקַבֵּל וְקוֹרֵא וְכוּ׳. ״עוֹמֵד״ — מִכְּלָל דְּיוֹשֵׁב הוּא? וְהָאָמַר מָר: אֵין יְשִׁיבָה בַּעֲזָרָה אֶלָּא לְמַלְכֵי בֵּית דָּוִד בִּלְבַד, שֶׁנֶּאֱמַר: ״וַיָּבֹא הַמֶּלֶךְ דָּוִד וַיֵּשֶׁב לִפְנֵי ה׳ וַיֹּאמֶר מִי אָנֹכִי וְגוֹ׳״!
It is stated in the mishna: And the High Priest stands, and receives the Torah scroll, and reads from it. The Gemara asks: From the fact that he stands, it can be understood by inference that until that point he had been sitting. But didn’t the Master say (Tosefta, Sanhedrin 4:4) that sitting in the Temple courtyard is permitted only for kings from the house of David, as it is stated: “Then King David went in, and sat before the Lord; and he said: Who am I, O Lord God, and what is my house, that You have brought me thus far?” (II Samuel 7:18).
כִּדְאָמַר רַב חִסְדָּא: בְּעֶזְרַת נָשִׁים, הָכָא נָמֵי בְּעֶזְרַת נָשִׁים.
The Gemara answers: As Rav Ḥisda said in a similar context: This took place not in the Israelite courtyard, where the prohibition against sitting applies, but in the women’s courtyard. Here, too, the reading was in the women’s courtyard, where it is permitted to sit, as it does not have the sanctified status of the Temple itself.
The question is based on a diyuk, that is, a close reading, that omed implies an action (and change in state) rather than a state itself. The kohen gadol stands. The implication is that until now, he has been sitting. But a peshat reading may be that he receives it while standing. And this is underscored by the repetition of the word omed in the next phrase, he reads it while standing. In this second phrase, he is not now suddenly standing while previously sitting, for we just read that he received it while standing.
The purpose is, rather, a contrast, when compared with the next Mishnah, and between actions. In this Mishnah, the kohen gadol both receives and reads while standing, while in the next Mishna, the king receives while standing but reads while sitting.