Wow, yeah, I just bought our V40 and it had only 1 key and it's a PCC one. I'm getting another, scheduled for April, but it's going to be close to 400 (euro) including labour, required booking into Volvo, and will take about 1 hour (though I was asked to expect 2 - 3 hours in total with wait times, etc.). All I can really tell that it will give me is the ability to save different presets to it (maybe another will also) and shows colours as to whether the car is locked or not or the alarm had gone off (and if you have the wings folding when you lock it...you kinda know over half of it).
So is it really worth it? I want to keys to have one in case I lock my key in (might seem hard to do but my lovely partner did it on a VW by throwing her purse too far in to the boot...with the key in it). Otherwise, I can't imagine any great benefit.