I won't draw any conclusions towards "Penta Magenta" vs Panther Pink since it's not included, but note that some Hi-Impact colours have different names than those accepted as being the same in America and Canada. My recollection of Penta Magenta comes from many years ago when my buddy wanted to build a model of a Panther Pink T/A Challenger, so he went to the local paint shop to have some mixed up in a spray bomb. When he picked it up, the shop had written "Penta Magenta" on the can and told him that this is what the colour was called in Canada. When he painted the model, the colour was definitely Panther Pink. So not proof, necessarily, but definitely anecdotal information. I haven't seen any proof one way or the other, but it would be interesting to see what the actual situation might have been. I wasn't old enough to know or care in 1970... ;-)

Also as a side note, the colours on the chart obviously didn't scan to be exact replications of what they were representing, so take that into account.