Question GPU Instancing & Material buffers

Hi, I'm working on a foliage rendering system. Foliage is placed on my terrain. My terrain is divided up into tiles.
Per tile I run a compute shader to produce instance data (position etc.) I then set a reference to that instance data buffer to the foliage material.
So for example I have a material for a grass mesh. That grass material gets the instance data buffer. Finally, that material is passed to a Graphics.DrawMeshInstancedIndirect call.
Now the issue:
If 2 or more tiles have the same foliage type, I use the same material. Now both tiles produce instance data => the material ping pongs between those 2 instance data buffers.
What's the best approach from here on?
Simply copy the material such that each tile has a separate material instance?
I've read a bit about MaterialPropertyBlocks, are those an alternative to copying the material?