The revised taskbar introduced with Windows 7 has been a real benefit to users, making it possible to always have frequently-used programs ready for action. However, not all developers account for pinned icons: for example, when updating iTunes, it is necessary to remove the icon, and then add it again after completing the update. Without doing so, you are likely to note the pinned icon, when right-clicked, is identified with a (2) after its name, which can be frustrating and seemingly impossible to correct: Windows does not make it obvious how to rename pinned shortcuts.
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Fix Duplicate Icons on Your Windows 7/8/8.1 Taskbar (Make Tech Easier)