Polycontrast is a variable contrast B&W paper for B&W negatives. As mentioned Panalure is for B&W prints from color negatives.
It's been mentioned in here that developer incorporated papers don't keep very well, so your paper may well be age/chemical-fogged.
The way to test would be to take two sheets or two partial sheets, develop and fix one, and only fix the other.
Mark them in some way first so you know which is which. After both are fixed compare them, if the paper isn't fogged they should look quite similar. If there is fogging it will be obvious.
As noted, you'll need to do the entire process in total darkness.
You may want to do the same test with the polycontrast, though you can use safelights for that.

If the panalure is only partially fogged, it may be a good candidate for paper negs in a camera.