Assorted Discus

I'm planning on buying some Discus in the not too distance future. Most places I look give the option of buying assorted Discus.

What is generally meant by this?

Are these fish born from mixed strain parents and therefore fail to fall into a specific strain themselves?

Or are they individual fish of assorted strains that aren't (for one reason or another) particularly good examples of that strain and so aren't sold as that strain?

Or are they good individual examples of assorted strains that are the odd one or two left over from a larger batch?

I hope I've made sense, I know what I mean!

Thanks in advance for all input.

Stuart.

Thanks Sue (yet again). That was the answer I was expecting and hoping for.

I assume that buying Discus this way could lead to a few bargains. The place I am looking to purchase from sell red/blue turqs, altum flora, blue diamond and cobalt blue for around £12 (3"-3.5" in length). But if I go and choose my own fish I could get some less common strains for the same money!

For those that don't know me, I love a bargain. 

Stuart.