Registry cleaner software will state that your programs will be confused by the duplicate entries, slowing your machines performance, but that is not true. Duplicate keys are made when you reinstall, upgrade or update software on your machine, including the operating system. Registry cleaner software will often claim these are an immediate issue, but in reality, they will just use up a few kilobytes of free space on your disk. Orphaned entries occur when you uninstall software and small fragments of registry entries are left behind.
Some are worth worrying about, and others are not. There are several common causes of registry errors. You can change registry key values manually using the built-in Windows Registry Editor (regedit) in order to improve performance or make Windows work the way you want, but you need to know what you’re doing or you can seriously damage your OS. The Windows operating system constantly refers to the registry for example, to open a program, install new software or change your hardware, Windows must check the values of certain keys. The registry contains two basic elements: keys and values. The Windows registry is a database containing important, machine-specific settings and information regarding almost everything in your computer - preferences, applications, users, attached devices and so on.
