Keyboard or hardware issue repeating characters

my keyboard is repeating character but it working fine on my friend's pc .....then i replace his keyboard to mine ..then also same problem .....then i changes keyboard setting.......and i also formatted pc............even after upgrading OS from windows 7 to windows 10 then also same issue...........even i replace with another hard disk which having win 7 same problem occur..........plz help..............where is the issue ...