After Lavan named the pile 'Yegar Sahadusa', why does the Torah see fit to add that after, he called it 'Gal'ed?
Ramban and Seforno: To teach us that he conceded to Yakov's wish that it should be called by its name in Leshon ha'Kodesh. 1
Tosfos ha'Shalem: Refer to 31:47:1:1.
Malbim (48,49), ha'Emek Davar: Lavan said that the testimony of the rock-pile is a mere witness for today, and not lasting testimony. Tomorrow we will be in our houses, and I cannot harm you. However, the testimony of the Mitzpah (that) you not pain my daughters, is only for the future
In what sense was the pile a witness?
Rosh, Da'as Zekenim (52), Hadar Zekenim (52): They inserted a sword in the pile, and said that one who transgresses will be stabbed with a sword and stumble on the Matzevah. Bil'am, a descendant of Lavan, crossed with intent to curse Yisrael. His donkey crushed his leg on the Matzevah (see Targum Yonasan on Bamidbar 22:24), and later he was killed through the sword. 1 "The witnesses' hand will be first [to stone]."
Tosfos ha'Shalem (1, from citing Pirkei d'R. Eliezer 36): David could not cross to conquer Aram until he broke the Matzevah [even though Aram had already transgressed the Bris twice
Moshav Zekenim: Rashi gave a rule, that whenever there is an Ed for a Bris, punishment is through the Ed. Therefore, Rashi explained (Bamidbar 22:24) that Bil'am's leg was crushed against a stone wall. He was killed be'Charev (Bamidbar 31:8), i.e. a sword known from before. Refer to Bamidbar 24:21:151:2 and the notes there.