In ffxiv, you are only allowed to launch 2 clients at a time. But, there is a way to launch 3 or more. It it a little complicated, so please follow these instructions exactly.
1. Grab Proc Explorer from Sys Internals from HERE
2. Run FFXIV and login to the game
3. Alt-Tab back to proc explorer. Find the FFXIV process and right click for Properties.
4. Copy the command line.
5. On your desktop or wherever, make a new shortcut. For the launch string, paste the command line you copied earlier.
6. Save and enjoy.
This shortcut will remain valid for quite a while (several days when I tested it).
This will allow you to run 3+ clients, which is really great for botting. You can grab the FFXIV Bot from a site like MMOViper.com and use it to bot a full party together. Pretty neat no? Check them out.