Unfortunately they exist, we know this. Personally I have experienced this at first hand with one of my models, even though I am not a world famous shaper.
We are all influenced by other shapers or trends, as I have said on many occasions. My surfboards are a mixture of different shapers’ techniques and shapes, but always with my personal signature. Those who know my surfboards will always recognise some of my personal details that they know are mine. It is the signature of each shaper that makes it unique.
A model sometimes develops over time, with experience of shaping, surfing, measurement and details, these make it easy to recognise its creator. When someone without scruples copies a model without rights or permission, they lack respect for all that work that the shaper had done. On the other hand I think that if someone copies any of my models there must be something that I am doing really well and it makes me proud.