I sometimes have to combine two strands because product is so flimsy that it doesn't really look well when finished. I have also found that it's really cool and exciting to combine two unlikely types of novelty yarn for a different effect - like a flimsy "fur" and eyelash, in complementary colors.
We should never be afraid to experiment. This is especially true if we have already invested money in a specific yarn or thread and we do not want to waste it.
I have heard that some of these yarns "shed" after a while and all that is left is the core thread, bare of furry strands. Some also lose their fur in laundering, even if it's done gently by hand.
Considering that, which I only just now really thought about, I really should make a wee patch in each brand or type that I have on hand, and just dip them into a small cup of dish liquid and tepid water, and see how they handle. At least, I could then include honest comments on the effects of laundering by hand.
Either way, they look great when they work out the way we hope, so it's worth the occasional bad buy. Go ahead - give the fake furs a try.