וַיָּבֹ֤א יְהוָה֙ וַיִּתְיַצַּ֔ב וַיִּקְרָ֥א כְפַֽעַם־בְּפַ֖עַם שְׁמוּאֵ֣ל ׀ שְׁמוּאֵ֑ל וַיֹּ֤אמֶר שְׁמוּאֵל֙ דַּבֵּ֔ר כִּ֥י שֹׁמֵ֖עַ עַבְדֶּֽךָ׃ (פ)
און גאָט איז געקומען און האָט זיך אַװעקגעשטעלט, און האָט גערופֿן אַזױ װי די פֿריִערדיקע מאָל: שמואל! שמואל! האָט שמואל געזאָגט: רעד, װאָרום דײַן קנעכט הערט.
Rabbeinu Bahya
A Kabbalistic approach: the reason that both here and in other instances the name of the addressee was repeated was to indicate that both the attribute of Justice and the attribute of Mercy had concurred that the prophet should be addressed in the manner to follow. As a matter of fact there are only four instances in the Bible of G’d repeating someone’s name when He called him (Genesis 22,11, 46,2 Exodus 3,4 and Samuel I 3,10).
Ramban
AND HE STOOD WITH HIM THERE. That is, the Eternal stood — something like it is said, And the Eternal came, and stood503I Samuel 3:10. — with Moses, meaning, that Moses entered into the cloud as he had done at first.504Above, 24:18: And Moses entered into the midst of the cloud.