About KeyPress in vb.net

How do we know if any key is pressed twice by the user

For e.g.
If user presses "A" key twice i.e. "AA"
then I want a messagebox to appear

And also I want to know that which key combination (one after the other) is pressed by the user

For e.g.
If user presses "K" key followed by "H" key
Then messagebox must appear

Actually I am trying to write some characters in another language based on user input in vb.net

Thanks in advance.