It look like that RE script for J4B does not create x64 corresponding links.
For example in location
/java/re/jdk/6u5/promoted/j4b/b18/j4b/bundles/windows-amd64
we can see only ...amd64.exe. We haven't x64 link.

x64 links are absent for linux-amd64 j4b bundles and solaris-amd64 j4b bundles also.

On the other hand we have x64 links for jdk/fcs bundles .
see /java/re/jdk/6u5/promoted/fcs/b13/bundles/windows-amd64/ for example.

So,
   - x64 links are created for SE
   - x64 links are NOT created for J4B.