I've not done it but until someone more knowledgeable responds here's my two cents. Pineapples are bromeliads, if you've ever separated a bromeliad pup from the parent it would be much the same. I'd take it out of the pot and see if the pup has some feeder roots yet, pull gently and see if you can work it away from the parent. If not, plant them both in a larger pot so the pup isn't contorted. I've grown several pineapple tops and gotten fruit from them but I've not had one make pups before fruiting.
