I have ran dual processor with JRE 1.3 and 1.2 and silk 18.104.22.168 without any problems. I have only spoken to one other silk dual processor user and they said they had an issue with it. I would think everyhing is at the OS level so the software, unless asking the OS how many processors cannot do anything except maybe code poorely with threading. If that was the case, I think there would be issues (like timing on the application) which would be evident when used on a much faster machine, say from a 200Mhz to a 1400 Mhz. Anyhow, NO I didnt have any problems with dual processor and WIN NT SP5.
I had issues this week with Windows 2000 and a dual CPU system. Turns out that VNC (remote desktop) and SilkTest 6.0 SP1 had reliability issues. When I used the NT boot.ini /ONECPU switch to disable the 2nd processor, the tests ran reliably as they do on my single CPU systems.
I use a dual processor for Java testing every day. I was also on 22.214.171.124 until recently. I have not noticed any Silk issues, but I vaguely recall some JVM issues with dual processors -- search the Sun bug database.