If someone else can put materia onto my char in the same sense of repairs, does this include stacking?

Say for example, I want some materia, I put the request up, maybe I go afk, go to shop, go to bed, w/e, some guy comes, throws the materia on, another guy comes, he tries the 2nd one, then someone else comes tries 3rd, fails, my item gone?

Is it just as fast as repairing, so someone could effectively spam materia and break your item, not sure if it mentions this, didnt read it all, but that be a bit annoyings