Does muffle the spell stack with muffle the enchantment or muffle from the sneak line? Do any stack?

I believe 1 muffle effect is all you need and adding another muffle is useless.

the sneak enchantment works better the muffle. i tested both using the glitch to get higher percentages and using muffle i was still heard walking slowly, with sneak i was neither seen nor heard while sneaking

i think sneak stacks but im not sure