Do you mean task manager and processes if so duplicate processes may cause a problem with speed depending on how much the value is under the cpu colum. If it is high ie above 40 then this will be a problem what is the process name of the process that is being duplicated.
But if you do mean device manager showing duplicate processors it just means you either have a dual core cpu (very likely) or you have two cpus on your motherboard. If you go to the start menu then computer then system properties it will tell you about your processor and other stuff!! But having two processors should make your comp nearly twice as fast in theory. (depends on lots of things to many to list)
But having two processors should make your comp nearly twice as fast in theory. (depends on lots of things to many to list)
Having a dual core doesn't. While some multi-threaded applications will run faster, it won't be twice as fast. However, your computer should be considerable quicker in multi-tasking sceenarios (again, not twice as fast though)