Firstly, if they are from a pet shop then they will be hybrids not Winter Whites. Hybrids can have some health issues such as diabetes so worth reading up on that a bit
I don't think you'll be depriving it if you just get a single one. If you've got the room for a second cage then you could get two and if they do fight you can separate straight away. There is lots of information on this forum about how to encourage pairs to stay together but even with all that they can still fall out and potentially injure each other