This could not be further from the truth. The reasons for this are simple:
a) The slabs are not cut from blocks in the same way as say onyx, marble or granite
b) Semi-precious stone slabs are made up of hundreds of individual sections/pieces that are assembled almost like a giant jigsaw puzzle and are set in resin.
While slabs may indeed look similar, this process basically makes it impossible for any two slabs to look exactly the same.