How to detect title of dialog first then only decide which script to be executed? VBScript

EVery process has a propery called ProcessType.  If it's 32 bit, this will have a value of x86, if it's 64 bit, this will have a value of x64.

So, you could rewrite your code like this.

sub InitialDialog

set w=sys.Process("RobotArm").WaitWindow("#32770", "MAIN PAGE",-1,1000)
set w1=sys.Process("RobotArm").WaitWindow("#32770", "Home",-1,1000)

if Sys.Process("RobotArm").ProcessType = "x86" then
    w = Sys.Process("RobertArm").WaitWindow("#42770", MAIN PAGE", -1, 10000);

else w = Sys.Process("RobertArm").WaitWindow("#32770", "Home", -1, 10000)
    w.Window("Button", "SKIP", 1).Click

end if

end sub 

Side Note... investigate NameMapping.  You can identify objects a LOT easier and a LOT more reliably when they are mapped.  Your "Home" page could even be contingent mapping where the choices of how to identify it are built in so you don't even need to do the "WaitWindow".