Telling multiples who's older

What do ya'll think about telling multiples who was born first?

We had someone tell us their first born twin would take advantage of being the oldest and used it against his twin brother whenever he could...so it got us thinking. We personally plan to tell them they were just born on the same day (if they are, if not I guess they'll know lol) at least until we feel they would treat eachother fairly.

Also, for any Mom's that has multiples already, what did you do and how did it turn out?