I live in Ireland, but went to Uni in Scotland. By chance I was placed in halls of residence with another Irish girl (from a different county). 5 years later, we were best friends. We decided to go backpacking in Australia and got our tickets. I said i'd sort out the visas and needed both of our passport details. Turned out that both Irish passports were 8 years old, both printed on 22nd April 1999, and our passports had only 1 digit separating them, so were printed 1 directly after the other. This was before each of us knew of each other !