Hi Sunnybrook, Welcome!
You have a two fold issue here. You mentioned the floor was sealed and impregnated. Replacing the tile is not necessarily going to gaurentee a matched finish, without duplicating the procedure that was used by the installer (depending on the products used).
If the sealer/impregnator added any type of sheen to the floor, then when the floor was etched, it ate right through the sealer/impregnator, thus creating a splotch, right off the bat.
As Karen and Maurzio mentioned rehoning would do the trick. I have matched factory honing using either 600 metal bond diamond pads, or silica carbide pads. The most consistent finish for the whole floor is accomplished with the honing powders, as suggested. Anything over 400 grit will be prone to showing etch marks again.