They could be still unusual because they are fake though! So it's definitely worth doing a quick Google search at least! Some of the methods used to scoot around Nintendo's CIC chip might be unique for example. This can be of significance to collectors sometimes, or even the community in general as it can help when designing modern day cartridges or flash carts.
Just for their significance as oddities, knock offs can be worth more than you think.
An example could be the Scorpion 16, a sega genesis/mega drive bootleg console. It's really just a pretty standard Mega Drive albeit, in a funky case. Those things sold for maybe £70 when I was a kid when a genuine console cost £120. Now the knock-offs go for crazy money! I wish I had bought one when they were basically throwing them away.
So sure, in reality they aren't the real thing but because they are relatively rare and as a curiosity, they sell for a lot