If the pistons that you ordered from Nissan are for your exact model, then [in theory] they should have the same dish, but sometimes they "supercede" some part numbers to reduce the variety of some parts, so you will need to take your sample with you when you go to pick the genuine ones up.
If they are not the same, then you can obvoiusly buy the wrong ones for a lot less & should decline to purchase deep dish ones at the "genuine" price.
If they ARE the right ones, then just grin & bear it. The nasty gash in your wallet will eventually heal, the painfull memory will fade, & you will be glad that you have the right part.

Is it possible to have a look at a variety of diferent A14/15 heads? If you can find a head with a smaller chamber, then cheaper pistons & a replacement "smaller chamber" head may even be the way to go.

I paid the Aussie equivalant [roughly] of $150 US for my non-genuine A15 pistons. Fortunately for me, the dish volume was the same as genuine ones.