Do I have to pay the same app twice?

I had an iPad 2 and I bought some apps.

Now I have bought a new iPad and I would install the same apps which I had in my old device.

In my new iPad I use the same Apple ID which I used in my old iPad.

If I try to install some app which I have already paid, I can push the INSTALL button and I have no problem (with apps like Noteshelf, neu.Annotate, etc...)

When I try to install Pages and Numbers (I had these two apps in my old iPad) there isn't INSTALL button, but there is BUY APP button.

Do I have to pay again these apps?

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