What do we learn from "u'Shetayim Delasos la'Delasos?"?
Rashi: Pesach ha'Heichal had two pairs of doors, like it says in Midos (4:1) ? two inside and two outside. The outer doors open into the opening, to cover the wall [on the sides of the opening], which was six Amos thick. Each door was five Amos ? half the width of the opening. It was Kanus one Amah inside the Mezuzah 1 . It turns out that five Amos of the thickness of the wall were exposed. When the outer door was opened, it covered the exposed five Amos. The inner doors open into the Bayis, to cover [the wall] in back of the doors. The entire Bayis was covered with gold, except for in back of the doors. R. Yehudah says 2 , also the inner doors open into the opening. I.e. the outer doors open towards the inside, and the inner doors open [towards the outside] into the opening (refer to 41:24:1:1).
One could explain that its thickness occupied one Amah along the Mezuzah. However, Malbim explains that it was attached to the wall one Amah into the opening. (PF)
Malbim: Even though the Rambam rules like the first Tana, Bayis Shelishi will be like R. Yehudah, for the verse implies like him. Even R. Yehudah holds that Bayis Sheni was not like it says here ? there the doors were half an Amah into the opening, and here they are at the beginning of the opening "Rochav ha'Ohel" (1). R. Yehudah learned from our verse only that the doors fold, but they were not exactly the same.
What do we learn from "u'Shtayim Delasos la'Delasos Shtayim Musabos Shetayim"?
Rashi: Each door was two doors (each two and a half Amos) with a hinge in between. It folds 1 into two and a half Amos, and its thickness was a half Amah.
Radak citing Bereishis Rabah 66:5: "Ach Yatzo Yatza" (Bereishis 27:30) ? after receiving the Brachos, Yakov left via folding doors, and stood in back of them until Esav entered; after, he fully left.
