"... The patch-in-place mode implies that when a version of the JRE exists on a machine, any updates belonging to the same JRE family will be done in place, meaning, the existing JRE will be patched with changes. A JRE is installed in patch-in-place mode by default. The default installation directory is c:/Program Files/Java/jre where n is the Java SE minor version number (for example, n = 6 for version 1.6.0_10).
For example, if a user has previously installed JRE 6u10 in the c:/Program Files/Java/jre6 directory, and now attempts to install JRE 6u14, the version 6u14 installer does not create a new directory. Instead, it updates the pre-existing c:/Program Files/Java/jre6 directory with the new 6u14 content. The user is left with the 6u14 JRE only. The 6u10 JRE no longer exists..."

La nuova versione di JRE, quando installata in "patch-in-place mode" (la modalità d'installazione predefinita), rimuove tutte le precedenti versioni di JRE presenti nella stessa directory.