Hi Lina,
HD means high density and HR means high resilience and these are two different grades of polyfoam. There is no HDHR polyfoam. You can read a little more about HD and HR polyfoam in this article and in this article.
There would be no way for me to know which mattress you are referring to since these materials (especially HD polyfoam) are very common in mattresses. The only way to track it down would be knowing the name of the manufacturer who made it.
Polyfoam (or memory foam) is never a natural material and is made mostly from petrochemicals. You can see the foam quality guidelines that I would suggest using in post #4 here and as you can see the polyfoam and the memory foam used in the Pure Crafted Beds are all high quality materials and there are no weak links in their mattresses.
The choice of materials in a mattress is always a personal preference and there are many different designs for each type of mattress so a mattress that works well for one person may be completely unsuitable for someone else to sleep on. The only way to know for certain whether any mattress is a good match for you would be based on your own personal testing or experience (see mattress firmness/comfort levels in post #2 here).
Pure Crafted Beds is a member here which means that I think highly of them and I believe they compete well with the best in the industry. You can see some thoughts about them in post #2 here
It would have been partly because the design of the mattress would have been a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and partly that you seem to prefer the “feel” of the materials that were in it.
Phoenix