Both Java and Adobe flash player, installed in many many computers, don't uninstall when updated, making simple updating beyond the average user.
As indicated, the presence of an old version of either alongside a new version doesn't necessarily remove any exposures to vulnerabilities in the old version/s.
Recommended procedure is to uninstall the old prior to installing the new. Adobe provide an uninstaller for just this purpose. I've found it necessary to install new versions in both IE and FF, if I want them in both.
OP, check out CCleaner for cleanup of old unnecessary items. Be careful not to tick every box prior to running it, though!