Reference for Chullin 205:27

מר סבר

but he who says [he is liable] twice, is of the opinion that an animal whilst alive does not stand to be dismembered into limbs, so that there are [present from the time of birth] the prohibitions of the forbidden fat and of trefah, and the prohibition of the limb [from a living creature] cannot be superimposed upon them.

Jastrow