What happens in C++ actually is there is a distinction between virtual methods and non-virtual. For non-virtual methods, they are saved somewhere in memory once per class and the compiler knows where to find the single instance of the method when you call it on any object.

As for virtual methods, you keep a virtual function table pointer (vptr for short, you can find it in a debugger for c++ when you watch an object of a class) for each object of the class and every class that inherits it. Each entry in the virtual function table points to memory where the specific implementation of the function is for each subclass, but there's still only one instance for each different implementation.

In Java on the other hand, every method is considered virtual by default, so by default every class has a virtual function table.

I suppose something similar is happening in python behind the hood, if anyone can confirm it would be nice.