Spawn all objects of a set at specific postion

Hey,

I'm making a game who take place in a supermarket, and i create sprite for twenty shelves for bread, milk, vegetables... I place on my layout spot for those shelves (spot are simple empty sprite object) and I want, on start of my layout, to create each of those shelves only once time at one of this spot.

I can create random shelves at those spots but and don't know how to create every shelves only once time.

Can sombody help me ?

I'll be trying to figure this out myself in a few weeks. Good luck...if nobody helps by then, maybe we can work it out together