No, you are correct, but I think Geordi mended it in some way. he must have been reading up on Android engineering!
You can see this must be the case because in 'Brothers' it is a small metal sphere, in 'Descent Pt II' it has become a small circle with a wedge removed, and by 'Generations' Geordi has altered it to become a one inch square object, with cylinders embossed on it!
Not only that, but he installs it by taking off the top of Data's head and fiddles with an access port, while the old chip went in a side panel under Lore's right ear.
Clearly, this is a different chip entirely!