Arvind,
Do you know what the policy is for the US? Immigration policies are a complete mystery to me here because they change constantly it seems.
Also, what is the big deal with many un-related individuals surnamed Singh or Kaur as photo-id, fingerprinting, and other methods are all part of the identification process?
I liked the comment about nonSikh names that are also common. Miller and Smith are more common than Singh -- if only by law of probability. If you try to explain this to bureaucrats they are genuinely confused by the argument.