A little sleuthing and yes, Duro is a tradename of Hwa Fong Rubber Inc out of Taiwan, which has been around since 1945 and produces tires for all sorts of applications.
In looking that up, I noticed that there is also a Duro Razorback which has been offered in 24" x 3.00" and which several have said was also identical to the Wildlife Leopard.
Funny and a bit discouraging to see how quickly and easily knowledge like this can get buried. But it looks like stocks of the 3" wide version with that name might have dried up at this point too. I’m only finding the 2.60" wide ones for sale now.
I’m sure you’re right about the molds still existing and just needing to order a run of a certain quantity of it, whenever supplies get tight again.