Windows allows you to adjust the keyboard repeat rate to avoid accidental doubling-up of letters. If this does not meet your needs then Windows also offers the more flexible Slow Keys feature.
Open the Windows Start Menu and click on the gear icon
Select “Devices” item in Windows Settings
Scroll down and click on “Devices and printers”
Find your keyboard item in the Devices and Printers windows and right click on it, the choose Keyboard Settings from the menu that appears
Click on “Speed” tab in the Keyboard Properties window
You can adjust the repeat delay (the length of time the computer waits before it starts repeating a key)
You can also adjust the rate at which the keyboard repeats the key. If this is too fast you can enable the Windows Slow Keys accessibility feature.
Click on “OK” button in “Keyboard Properties”