I hope that nobody has already posted this (so admin please feel free to lock etc)
I was playing today and had already completed my first 8 Guildleves in Ul'Dah when I took the ferry over to Limsa....
Went to speak to the Guildleve guy there and got 8 more! Less than 24 hours after I had completed my other. He let me trade my old ones for better rewards - I was stoked!
Just got to get to other city now to see if it works again.
O btw it also worked for crafting too!