Halocho #2240 - The Sandek only holds the baby once

The person who holds the baby during the Brit Mila is called a Sandek.

The custom is that the father never honors the same person twice with Sandeka'ut. (*)

On the other hand, the custom is to always use the same Mohel, if he is available.

Even if  it was assumed that the original Mohel would be out of town, and another Mohel was asked to officiate, the original Mohel has precedence, if he's back in town on time.

Source: Kitzur Shulchan Aruch 163:1

(*) The reason given is that being a Sandek is a Segula for prosperity, and we want to "spread the wealth". Similarly, each Cohen was only given one opportunity to bring the Ketoret (Incense) in the Bet Hamikdash, since it's a Segula for prosperity.

- Danny
Wednesday, Shushan-Purim-Kotton, 15 Adar-I 5779

 וְיֵשׁ לְאָדָם לַחֲזוֹר וּלְהַדֵּר אַחַר מוֹהֵל וְסַנְדָּק הַיוֹתֵר טוֹב וְצַדִּיק

נוֹהֲגִין שֶׁאֵין נוֹתְנִין סַנְדְּקָּאוּת לְאִישׁ אֲשֶׁר כְּבָר הָיָה אֶצְלּוֹ סַנְדָּק בְּבֵן אַחֵר

 אִם כִּבֵּד לְמוֹהֵל אֶחָד, אָסוּר לַחֲזוֹר בּוֹ וּלְכַבֵּד לְאַחֵר, שֶׁנֶּאֱמַר שְׁאֵרִית יִשְֹרָאֵל לֹא יַעֲשׂוּ עַוְלָה וְלֹא יְדַבְּרוּ כָזָב

 וְאִם כִּבֵּד לְאֶחָד וּבְתוֹךְ כָּךְ הָלַךְ זֶה הַמּוֹהֵל מִן הָעִיר וְחָשַׁב הָאָב כִּי לֹא יָבוֹא לִזְמַן הַמִּילָה וְעַל כֵּן כִּבֵּד לְאַחֵר וּבְתוֹךְ כָּךְ בָּא הָרִאשׁוֹן, יְמוּלֶנּוּ הָרִאשׁוֹן