so I went through the Sugya of MM. Mechaber and mb both don't explain what shtei min means as you said. The Aruch H'Shilchan says as well that you cannot be yotzei with two of same min... However I didn't seem to find anyone who holds you can... RabeInu Chananel says you can be yotzei but the taste has to be a little different. Rav elyashiv says similar, you can be yotzei same if they are cooked differently etc. One cooked, one roasted... No-one seems to say that you can be yotzei with 2 exact same items... ?
Okay..
The Mechaber and MB don't mention a word about two minim. (The lashon h'mechaber actually implies the same min is also fine.)
What Rabbeinu Chananel are you referring too?
The פרי מגדים בראש יוסף raises the question and is leaning towards one min is good enough, the Batchutcher Rov in A"A also speculates.
As I said the Aruch H'shilchan is the only one of the previous poskim who strictly requires two minim with certainty. (He has a diyuk from a Rambam, which others aren't maskim with.)
The מהרש״ג and אפרקסתא דעניא are both of the opinion that it can be two of the very same, and the ציץ אליעזר is also arguing very strongly against the Aruch H'shilchan, going as far as saying that even one large portion which can be divided for two is perhaps also good enough.
The Belzer Rov Reb Yisochor Dov Ztz"l gave two slices of the same cake for Mishloach Manos, which was perceived by the poskim of his chassidim as מעשה רב that it must not be two minim.
But פוק חזי מאי עמא דבר, the minhag h'olam is definitely to be makpid on two minim.