This post is slightly off topic, but it is an important issue and is interesting.
The proper spelling of names is critical to the kashrus of a get. If someone has a name which is found in the Torah, the name must be spelled as it is found in the Torah. Sefer Get Mesudar Shaar 7, Siman 15, Se'if 11 discusses how to spell Yisachar.
(We pronounce the name spelled Yud-Shin-Shin-Kaf-Reish as Yisachar, even though it is spelled as Yisaschar. In Breishis 46:13 Yisachar has a son named Yov, and in Bamidbar 26:24 his name is changed to Yashuv. There is a midrash quoted by Daas Zekanim on Breishis 30:18, that when Yissachar found out there is an avodah zarah called Ov (which apparently is the same as Yov), Yisaschar gave his son one of the shin's from his own name, changing Yov to Yashuv and Yisaschar to Yisachar. Because of this midrash, in Volozhin they read Yisaschar until Parshas Pinchas, when Yov's name is given as Yashuv. See Nefesh Harav p. 308.)
Get Mesudar says if someone is called to the Torah and signs his name as Yisachar, we write Yisachar (only one Shin) in a get. However, many people sign there names with 2 shins. The Pesher Davar on that sefer says in that case, where he's called to the Torah with one shin but signs his name with two shins, we write in the get "Yisaschar dimiskirei Yisachar." I do not know how mesadrei Gitin write Yisachar in a get.
Similarly, two years ago the chazan in our shul when we benched Rosh Chodesh Av just said "Av." Our Chazan for the Yamim Noraim was very upset and told me "He should have said Menachem Av." I showed him the Aruch Hashulchan in Hilchos Gitin, Even Haezer 126:16: Av - we don't write Menachem Av because our custom to call it such in our correspondences and when we bless the month is only as a consolation that we should merit, iy"h bb"a but its name is only Av. So we find in the beginning of maseches Rosh Hashana. If he wrote [in the get] Menachem alone (and not Menachem Av) there is an opinion that is it is Kosher bidieved since it is well known that Av is called Menachem. I have my doubts about this because true, in books and approbations by Sefardic sages they are accustomed thus [to call it Menachem] we [Ashkenazim] do not have that custom. Some write to write both [Menachem Av] and I certainly agree if it was written this way it's Kosher bidieved since this how we bless the month in our countries and what we write in letters.
Below is a reproduction of a get, from Psak Hadin beinyan He'ach veha'achot by Chief Rabbi Shlomo Goren (Jerusalem, Tevet 5733). The left and right sides are cut off in the book.