There are many setting currently linked when using dual extrusion that in my opinion should not be.
For example:
Infill settings, speed settings, support setting etc. I haven't checked them all, but it seems there are many which should not be linked.
Also I find it essential to have an indicator of linked and unlinked settings. A different color or an icon.
An even better approach would be to have a link button next to each setting which will allow the user to set what should and what should not be linked.
For example: If I print a part with PLA and Nylon at the same time, I would rather have different speed settings for both materials.
I hope I explained it well enough.
Thanks!