Depends when you bought them and who you bought them from, I would say. John Neal have been good at replacing nibs from defective batches in the past, so if you bought them there at a time when there was a recognised problem with the nibs, it would be worth contacting them and asking if they can be replaced. I don’t know what PIA is like, but they’ll probably be sympathetic too. If you bought from somewhere else and it was a while ago, I think you may be out of luck. But if you only just received them and the nibs don’t work as they should, then you should get them refunded or replaced.
Are you talking about a considerable difference in widths? In my experience, in a lot of pointed nibs there’s a difference between the tines but not enough to cause issues.