Description of problem:
After anaconda upgrade on s390x and creating new boot loader configuration during the upgrade, some boot options are listed twice in kernel parameters section of zipl.conf (for example rd_NO_LUKS, KEYTABLE=...):

[linux-2.6.32-431.el6.s390x]
        image=/boot/vmlinuz-2.6.32-431.el6.s390x
        ramdisk=/boot/initramfs-2.6.32-431.el6.s390x.img
        parameters="root=/dev/disk/by-path/ccw-0.0.3161-part3 rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD  KEYTABLE=us cio_ignore=all,!0.0.0009 SYSFONT=latarcyrheb-sun16 rd_DASD=0.0.3161 rd_NO_LVM rd_NO_DM dasd=0.0.3161  KEYTABLE=us rd_NO_MD crashkernel=auto rd_DASD=0.0.3161 SYSFONT=latarcyrheb-sun16 rd_NO_LVM rd_NO_DM"

Version-Release number of selected component (if applicable):
anaconda-13.21.215-1.el6

How reproducible:
always

Steps to Reproduce:
1. install RHEL-6.4 on s390x
2. start graphical (vnc) installation of RHEL-6.5
3. select "Upgrade an Existing Installation" when asked
4. select "Create new boot loader configuration"
5. zipl configuration screen is displayed with "Kernel Parameters" field pre-filled like this:
"rd_NO_LUKS LANG=en_US.UTF-8 rn_NO_MD KEYTABLE=us cio_ignore=all,!0.0.0009 SYSFONT=latacryheb-sun16 rd_DASD=0.0.3161 rd_NO_LVM rd_NO_DM dasd=0.0.3161"

6. do not make any modification, click Next
7. finish the upgrade and reboot to installed system
8. check /etc/zipl.conf

Actual results:
Duplicate kernel parameters in zipl.conf

Expected results:
Each parameter is listed only once

Additional info:
* system boots correctly with duplicate boot options
* unable to reproduce on x86_64 (there is no zipl configuration screen)