Originally there were three versions to Alcohol.
Alcohol 52% - The Virtual Drive.
Alcohol 68% - The Burning Software
Alcohol 120% - Both Parts Joined Together.
I am not sure what happened to Alcohol 68% they seem to have stopped developing it seperatly.
I am not sure if they are updating Alcohol 52% seperatly. I know it gets updated through Alcohol 120% though.
You can have up to 31 virtual drives at any one time.