By this reasoning, I count three replacement for three pairs. If you don’t count the first one that leaves just two. Not a very solid way to do the basic arithmetic, really, but that’s fine and dandy with me.
You are just following a different ("wrong") line of reasoning. I suggest you read posts #17 and #18 (and #15 (mine) as well again)...
If someone for example states, that he needs three pairs of rubbers per year, it is imperative to make a "cut" somewhere in order to know when to start counting (you could make that "cut" at the end of the season or at the end of the calendar year or at any given time; you just need to know when you had made that "cut")!
For players who play/ practice all year round: At the beginning of the season (or calendar year) the first pair of rubbers are the, let's say, "originals" and replace therefore "nothing"
(of course you had worn out rubbers on the blade, but as I said, it is necessary to make that "cut" somewhere in order to know when to start counting). So when the "original" rubbers are worn out, they will be
replaced for the first time with the second set of rubbers, and when the second set of rubbers are worn out, they will be replaced with the third set of rubbers. Therefore the "original" rubbers from the beginning of the season (or calendar year) were
replaced twice, while at the same time you have the
third pair of rubbers (of that year) on your blade.
Even though that was a rather long post, I'm fairly confident to say, that the majority of the people are able to follow that line of reasoning and agree with it. If you don't however, well, than that's fine and very dandy for me, too.
By the way: It is quite useful being able to distinguish between plain counting and replacing things...