Replacing existing software with newer rpm's

Just purchased an HP PSC 2355 printer, scanner, copyer.
HP{ provides a driver for Linux. It requires updating
existing software with later versions. I have found the
required later versions as rpm's. What happens to the
old software when I install the newer versions. Is it
left in the system and I have to remove it, or is it
automatically replaced?

TIA

Clay Stapleton