Hi slippyfish. It's a very interesting example you have posted, thanks for showing us this and including background information. This has happened to me too.
Looking at both Kestrel and Orbea designs, in legalese "in situ", they appear to be more coincidence than copy. They are the same configuration product (trapezoidal diamond composite frame time trial bicycle), it is logical that design - engineering - style - manufacturing solutions have similar embodiments. There appear to be minute but significant differences in their design - engineering - style - manufacturing embodiments that probably can be amplified by explanation. It is typical in highly competitive niche product categories where individual offerings are differentiated by minutia, differences minimal to the general public, that similarities occur in new product development.
Also, just topically, designs that have been shared and copied via Chinese factories usually have been more faithful copies.
It is true that factory tours can lead to design copy; I've done it but at a detail level (really cool gasket design attachment molding detail...) and seen similar example where someone copied a small design detail from me, both via same plastics molding plant. One time, some one called me asking permission to copy a design detail they had seen at our plastics molder!
I have seen new technology startup with an obvious copy, but badly done, of one of my designs. President and I discussed it, but his assertion was that the copy product could be shown, marginally, to not be a competitor, and the cost and time to pursue IP litigation wasn't worth it. I have seen other designs identical to some of my rejected design sketches: evidence that given a set of problems, someone may come up with similar design solutions.
Incidentally, Kestrel used to use a local company to make their molds. They were appropriately secretive within the factory, concealing certain projects (i.e. Lamborghini, coffee creamers) from wandering eyes.