Ah, but they wouldn’t be exactly the same, especially in the earlier filial generations because of recombinant genetics. Especially if these sisters came from unstabilized polyhybrid parents, there’s absolutely genetic variation in there. That would mean hitting these gals with the same male opens up two pools of new recombinant possibilities that may or may not be similar to each other. That’s why I’d consider them F1’s but I dig the “cousin F2” designation too hahah.
I would expect it to be pretty similar. The only difference being two mothers, you’re probably just looking at more total recombinant possibilities in those F2’s compared to a single mother, so probably a bit more variation depending on how many seeds you’re poppin’.
This is a cool debate I hope more folks chime in on this