Most samples bought off a web-site would be sold to multiple people, i.e., many people will have exactly the same samples as you do. Mostly, the deal is that you would be able to use the samples your music (commerical or otherwise) without paying any additional fee, but you are not allowed to re-sell them as samples. However, you should read the license agreement to be sure. I think if you want samples that no-one else has, you likely have to pay considerably more and probably negotiate directly with the producers
