[CentOS] how to access lvm inside lvm

I have a centos 5.6 server that has xen domUs installed on their on
logical volumes. These logical volumes contain their own volume groups
and again their own logical volumes. I want to access the domU logical
volumes and tried this:

[root at kr ~]# fdisk -l /dev/VolGroup00/LogVol02

Disk /dev/VolGroup00/LogVol02: 274.8 GB, 274877906944 bytes
255 heads, 63 sectors/track, 33418 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

                    Device Boot      Start         End      Blocks   Id  System
/dev/VolGroup00/LogVol02p1   *           1          13      104391   83  Linux
/dev/VolGroup00/LogVol02p2              14       16709   134110620
8e  Linux LVM

[root at kr ~]# kpartx -a /dev/VolGroup00/LogVol02
[root at kr ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 62 Apr 26 02:19 control
brw-rw---- 1 root disk 253, 12 Apr 30 00:45 LogVol02p1
brw-rw---- 1 root disk 253, 13 Apr 30 00:45 LogVol02p2

But when I try make the domU volumegroup accessible I run into problems:

[root at kr ~]# vgscan
  Reading all physical volumes.  This may take a while...
  WARNING: Duplicate VG name VolGroup00: Existing
hxNFYw-c1Z6-DB99-SiiK-yRas-eXiI-1w27Z0 (created here) takes precedence
over KmwQTQ-jT19-lvvu-H6d0-i4T3-s5Jw-JHnx0M
  WARNING: Duplicate VG name VolGroup00: Existing
hxNFYw-c1Z6-DB99-SiiK-yRas-eXiI-1w27Z0 (created here) takes precedence
over KmwQTQ-jT19-lvvu-H6d0-i4T3-s5Jw-JHnx0M
  Found volume group "VolGroup00" using metadata type lvm2
  Found volume group "VolGroup00" using metadata type lvm2

How can I now vgchange to the domU volume group as vgchange does not
take the UUID as an argument, just the volume group name...?

Regards,
Peter