Hi tigerlilly,
There is more about the different ways that one mattress can “match” another one in post #9 here but any differences between two mattresses in the type of materials or in the other specs or components (layer thickness, layer firmness, the type of cover and quilting etc) can change how a mattress feels and performs yes.
There is more about how blended Talalay and 100% natural Talalay compare in post #2 here. I would keep in mind that all latex is a durable material relative to other types of foam so it wouldn’t “compromise” durability but if the Talalay is made by Latex International then in the lower ILD’s the 100% natural would be somewhat less durable than their blend. Softer materials are also less durable than firmer layers with any type of material but of course this is part of the tradeoffs that are part of any mattress purchase because most people need some softer layers in their mattress to provide good pressure relief. The choice between different types of latex would be a personal preference.
There are many online and local manufacturers (depending on the area) that sell either one or both so you may just have been looking at the ones that sell Talalay and somehow missed the ones that sell Dunlop.
Phoenix