You won't believe the number of people who go by nicknames, middle names, etc. One friend of mine goes by a nickname. But he registered himself with one airline as John Smith and another airline as Joseph Smith. Why?!? And yes, at least once he had an itinerary with both airlines in it. Definitely a problem.

Then there are slight discrepancies. Another friend was almost denied boarding overseas once. Her legal name is Sandra, her nickname is Sandi. She booked under Sandi. The airline almost didn't give her a boarding pass.

People don't understand how important LEGAL names are!