sam4 according to rav Karp mechaber of hilchos shabbos beshabbato and Rav Simcha Kook Shlita Rav Elyashiv said we was just pointing out the possible problems and he himself does not hold that min Kanaf is on two strings. (you can confirm it from them)
And the yam shel shlomo in Yevamos 1 siman 3 and Artzos Hachaim (malbim) OC 9 5 (it is brought down in Mishna Berura) Chazon ISh siman 3 Ois 25 Shu”t Yeshuas Malco sima 1 and the maharsham all clearly hold there is no problem of min canaf