There are plenty of plants that appear to look like Big Mouth - after all it just happens to have bright red big traps and grow in a tight clumping rosette. Unless the plant is a labelled though, you cannot just call it Big Mouth because it happens to look a bit like one. The plant originates from Triffid Park, so it's unlikely a DIY store in the US will be selling it, especially unlabelled.
Dentate/dente can apply to any shark toothed cultivar according to the ICPS, so it safe to call any such plant Dentate, even if they aren't genetically identical. I don't make the rules up!