Mixing yarn types

I am ready to CO another felted bag. I have two brands of yarn, one that felts fast and one that needs extra time. If I use these two (not twined but one after the other), will my bag be lopsided or smaller in places? I’m hoping that when I block it I can even it out. :shrug:

If the desparity between the two is substantial, I’m not sure blocking would make everything right in the end. Could be an interesting design property though…it might look cool like that. I’d knit a swatch using both yarns and felt it so you can get an idea of what it will look like afterward.