What happen when buying bundle with already own item ?

I wonder this since Emporium appeared : If i buy a bundle with part i already own, how much will i end paying exactly ?
Let's take the skel pets bundle as an exemple. I already own 4 ou the 6 pets in the pack.
The whole bundle cost 2499
The remaining pets cost 1298 (2x 649)!

So if i buy the whole bundle, will it cost me 2499 ? Or will it only cost me 1298 ? Or something else ?