Unfortunatelly copycats existed and will continue to exist at all times. Of course it's not cool to see when your work is being shamelessly copied and especially if it's put on sale for significantly lower price than yours. All we can do is to try to compete with quality.
I also have found shameless copycat, who copied one of my model to the smallest details, even presentation is very similar. It's not nice, but i won't loose my sleep over it.
My model: https://www.cgtrader.com/3d-models/household/other/electrical-installation-set
Copycat's model: https://www.cgtrader.com/3d-models/electronics/other/switches-and-sockets-4c9e6f57-b910-4436-bb8e-7155ebef3956