The dwarf platies would be the same to breed as ordinary platies but I wouldn't keep them together as they'd likely hybridize (What species are the dwarf platies you are reffering to? If they are the same species then it doesn't matter but if they are something else, you shouldn't let them cross breed.). Also, not all livebearers breed in the same way. They aren't all your typical guppies, platies, swordtails and mollies... There's halfbeaks and limias and goodeids and brachy etc Well I suppose it's all similar but not the same and deffinately not always as easy.