Btw a second coming is just a Christian as the idea of moshiach itself- ie it’s a Jewish idea too. Sorry you haven’t seen it. Rashi on Daniel, and also Medrash on how moshiach will resemble the goel rishon Moshe Rabbeinu, by first being revealed, then concealed, then revealed again. If you want exact lshonos I quoted them early on in the 5 potential candidates thread.
The Rebbe also wrote in reshimos about Eliyahu hanavi (why should we expect moshiach daily if Eliyahu hasn’t come yet) we don’t know if he’ll come in the first stage of moshiach (when he’s revealed to those that know him) or the third stage- when he’s revealed to all. (Middle stage I think was fighting the wars of Hashem- don’t trust me, find and post it- haven’t seen it in over a decade i think)