What is the exact error? Something about not being able to start 3D acceleration?

I see this occasionally, not so much when starting my 5 instances with Keyclone (though it has happened this way), but sometimes I have one of the warcraft instances error out and I need to restart it manually, and I see this error. Once it starts happening I generally need to wait a while or close and restart my instances.

Do you get this consistently on startup, with your second window? Once you get this message, can you start an instance of warcraft manually or do you get the same error message if you do that?

Can you reproduce the error by starting multiple instances of Warcraft manually, not using Keyclone, quickly one after another?

If yes to the last question, you might want to try working around this. Keyclone doesn't have a setting in the command editor for placing a delay between starting up the instances, but it would be pretty easy to write a .vbs (Visual Basic script) or .bat (command batch) file to do this. For instance,

Code:
Set oShell=CreateObject("Wscript.Shell")
oShell.run "C:\wo\wow.exe"
Wscript.Sleep 8000
The above code, saved to a .vbs text file, will start the wow.exe executable located in C:\wo and then wait 8 seconds before exiting. I can't check this with keyclone at the moment since I'm in a huge queue to get in the server, but I'd be surprised if Keyclone didn't accept running a vbs file instead of the WoW executable directly.