The same product can be realized by different structures, just like "motor" has existed for a long time, but now there are many patents for "motor"!
The object of patent protection includes "a new technical scheme obtained by improving the existing technology". It shows that anyone can continuously improve the existing technology (product), and the new scheme obtained after this improvement can apply for patent and have the opportunity to get authorization!
Any country's patent application examination needs to search all the public documents in the world, and then evaluate the novelty and creativity of the applied technical scheme. So if you have the information about the original Japanese bladeless fan, you can compare it with the invention patent disclosure scheme authorized by Dyson. If you think there are creative problems with the patented technology, you can use the information in your hand as evidence to declare that patent invalid. The premise is that your information must be valid before the filing date of the patent application.