I think Real-SS has it right. I was at the hobby shop yesterday and got that same story. The shop guy told me that essentially the Parklite stuff is simply relabeled Ultracoat Lite and comes from the same place.
I was interested because I saw some transparent purple. It looked like a perfect match for a transparent purple SIG covering I had used on a Cardinal--but didn't hold up well and needed recovering. But the transparent purple seems to come only in the thinner Ultracoat (Lite), so didn't help me....
For those now having to "relearn their covering techniques" the Ultracoat rolls are about 2" narrower than the Monokote rolls.