The Rama (Rabbi Moshe Isserles, Poland, 1525-1572), in his glosses to the Yoreh De'a section of the Shulhan Aruch (Siman 265), cites from Rabenu Peres (France, 13th century) that one should not serve as Sandak on multiple occasions for one family. (The term "Sandak" refers to the person holding the infant during a circumcision.) The basis for this practice, the Rama explains, is the notion that the Misva of serving as Sandak is compared to the Misva of offering Ketoret, the incense in the Bet Ha'mikdash. The Sages teach that offering incense had the effect of making a person wealthy, and for this reason no Kohen would ever offer incense twice, so that all Kohanim would be granted the opportunity to earn wealth. Similarly, the Rama writes, it is proper not to serve as Sandak on multiple occasions, at least not within one family, so as not to deny others the opportunity for wealth provided by this great Misva.
The Gaon of Vilna (Rabbi Eliyahu of Vilna, 1720-1797), in his commentary to the Shulhan Aruch, disputes this ruling. He writes that were this practice to have stemmed from the comparison between serving as Sandak and offering incense, then it should require never serving as Sandak more than once in one's lifetime, even for different families. Just as a Kohen was not permitted to offer the incense more than once in his lifetime, in order to allow others to reap the benefits of this Misva, so would we have established that no person should serve as Sandak more than once. Since no such custom exists, the Gaon contended, we must conclude that it is not based upon the comparison between this Misva and the Ketoret.
The Gaon therefore claimed that this practice has its origins in the famous Last Will & Testament issued by Rabbi Yehuda Ha'hasid (Germany, 1150-1217), which includes numerous guidelines that the author advised his family to observe. It is unclear whether these rules were intended only for Rabbi Yehuda Ha'hasid's family, or for all Jews; in particular, it is questionable whether Sefaradim accepted these laws. Therefore, the Gaon of Vilna and many other authorities have ruled that one may, in fact, serve as Sandak on multiple occasions, even for children of different families. These authorities include the Noda Be'yehuda (Rabbi Yehezkel Landau of Prague, 1713-1793) and Rabbi Eliyahu Mani (Baghdad-Israel, 1824-1899). Although Rabbi Haim Palachi (Turkey, 1788-1869) held that one should not serve as Sandak twice within a period of twelve months, Hacham Ovadia Yosef disagrees. In his view, to the contrary, serving is Sandak is a great Misva that yields significant rewards, and one should therefore not abstain from serving as Sandak on multiple occasions, even within a short time-frame.
Summary: It is permissible for a person to serve as Sandak twice, or on multiple occasions, even for children of one family, and even within a short time-frame.
See Yalkut Yosef, Sova Semahot, Vol. 2, page 78
