Cloning creates a new JS object (so it uses some memory, but rather small). The image data is reused without cloning.
If you want to dynamically modify the number of repeat-s, DO NOT clone the texture every time. Cloning is done only once, then you can freely change the repeat of each material’s texture.
I will prepare an example with UV.
Edit: here is the example with UV modification (the size changes every second, only one texture is used):
https://codepen.io/boytchev/full/wvYeMrG
Edit 2: I also modified my previous example (the one with 6 cloned textures) – now it has dynamically changed size too