Could we have a discussion on the idea that "Two things can't be the exact same."

I don't really know what branch of philosophy this would fall under, but I've been intrigued about this idea for a while now. <br><br> 1. If everything is made of atoms, then theoretically, everything has to have some sort of weight to it. No matter how small that weight is, the concept of "weightlessness" would then be an impossibility. <br><br>2. If two objects have even the smallest amount of weight, then you could never place them in the *exact* same position as the other, because the weight of one object would outweigh the weight of the other and throw off both positions. Again, no matter how small that difference in weight is. <br><br><br>So, if that logic is correct, then we could never have the exact same positions, weights, etc. So, then it's not really accurate to say "Two things can be exactly the same". As one object will always outweigh the other, no matter how small that difference in weight is. <br><br><br>Could anyone expand on this, or help direct me to a branch of philosophy where this is discussed?