ROB
As others have pointed out, the machlokes predates Rabbinue Tam SO opening up earlier sets of Tefilin wouldnt have resolved much since they’d find “Rashi” sets and “R”T” sets long before Rashi/R”T
There are many things that different segments of kala yisroel do differently. IT wouldnt be surprising if you learnt through a sugya and came to a conclusion that say the correct approach is to say eat in Sukka on shemini atzeres.
In generations from now if that shita becomes known as the “Shitas ROB” Some might ask how can it be a machlokes? What did Rob’s parents/grandparents do?
Again, like all analogies this one is flawed. But the idea that there is machlokes in klal yisrtoel and different poskim go through a sugya and come out one way or the other isnt surprising in of itself