If you have already installed a program can you install it again? does the installation install over the?

original? i already installed adobe flash player and my browser said it would be better if i install a newer version or something. I downloaded the installation program into my download folder and it had the same name as one i had before which is why it was changed to install_flash_player(2). anyway i installed this new flash player. Since it did not tell me to uninstall my original flash player before installing the new one does that mean it just replaced it? or does it mean it upgraded it? by the way i have "adobe flash player plugin" installed. is "adobe flash player plugin" the same as "adobe flash player"? is flash player implied to be a plug in? did i just patch up a plugin?