פירוש על מנחות 80:10

It is involved with [violating] "do not add"; it is not considered an action: As since he transgressed a prohibition, it is not considered an action; so [only] at the time of the cutting of the first [strings], is it the making [of the second strings]. So it is not similar to that [case] in the first chapter of Sukkah 11a, in which we do not say their cutting is their making. And this requires [further] investigation.