Why does initramfs of older Red Hat Enterprise Linux 6 release getting corrupted during dual boot installation of new release?

Issue

• The system is installed with Red Hat Enterprise Linux 6.5 with the following partitioning.

zerombr
clearpart --all --drives=sda
part /boot --fstype=ext3 --size=1024 --ondisk=sda --asprimary
part pv.01 --size=62464 --grow --ondisk=sda --asprimary
volgroup sysvg pv.01
logvol swap --vgname=sysvg --name=swap --fstype=swap --size=2048
logvol / --vgname=sysvg --name=root1 --fstype=ext4 --size=24576
logvol /root/unused --vgname=sysvg --name=root2 --fstype=ext4 --size=24576
logvol /home --vgname=sysvg --name=home --fstype=ext4 --size=10240

• Have an unused logical volume called root2.
• Then installing Red Hat Enterprise Linux 6.6 into this using a kickstart with disk setup like this:

part /boot --noformat --onpart=sda1
part pv.01 --noformat --onpart=sda2
volgroup sysvg --noformat
logvol swap --vgname=sysvg --name=swap --useexisting
logvol /root/unused --vgname=sysvg --name=root1 --noformat
logvol / --vgname=sysvg --name=root2 --fstype=ext4 --useexisting
logvol /home --vgname=sysvg --name=home --noformat

• Only swap and the root2 volume get reformatted and Red Hat Enterprise Linux 6.6 is installed into root2.
• When done, root1 has Red Hat Enterprise Linux 6.5 and root2 has Red Hat Enterprise Linux 6.6.
• Then the file /boot/grub/grub.conf file is modified to have the 6.5 and 6.6 entries so one can boot either OS since /boot partition contains the boot files for both.
• The problem is seen when installing Red Hat Enterprise Linux 6.6 into root2 volume. During the install, the /boot/initramfs* file for Red Hat Enterprise Linux 6.5 is recreated but since it cannot get to the kernel modules under /lib, this file is not complete and when trying to boot to 6.5, one get a panic.
• Why the install of Red Hat Enterprise Linux 6.6 try to rebuild the 6.5 initramfs file?
• Is there a way to keep this from happening during the install of another OS version?