I have normal java installed already. now I want to install a software which requires the 2:
- Java Development Kit 6 or higher (http://java.sun.com/javase/downloads/index.jsp)
- Maven 2.2.1 or higher (http://maven.apache.org/)
Should I remove normal java to install the Development Kit?
No you do not have to. However JDK contains the runtime environment (JRE), so if you can safely remove it, if you wish so.
EDIT: Although, as Johannes points out, you may need to take care of PATH environment variable and file associations on Windows.