RAID1 (MD) partition - strange scenario after installation

Binary package hint: mdadm

My original partitions looked somehow like this (installation):

RAID1

md0
sda1, sdb1

md1
sda2, sdb2
(lvm)

md2
sdc, sdd
(lvm)

After first reboot it reodered to:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 md1p1[1]
      1951680 blocks [2/1] [_U]

md1 : active raid1 sdb[1] sda[0]
      486433728 blocks [2/2] [UU]

md2 : active raid1 sdc[0] sdd[1]
      488385472 blocks [2/2] [UU]

What causes this? I used 10.04.1 installer. This is not happened with 10.04

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: mdadm 2.6.7.1-1ubuntu15
ProcVersionSignature: Ubuntu 2.6.32-24.39-server 2.6.32.15+drm33.5
Uname: Linux 2.6.32-24-server x86_64
Architecture: amd64
Date: Thu Nov 25 12:09:25 2010
InstallationMedia: Ubuntu-Server 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.2)
MachineType: Intel Corporation S3420GP
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-24-server root=UUID=09a46afb-1ab1-43cc-aa05-1f9c7d5d7197 ro quiet
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: mdadm
dmi.bios.date: 04/29/2010
dmi.bios.vendor: Intel Corp.
dmi.bios.version: S3420GP.86B.01.00.0042.042920102218
dmi.board.asset.tag: ....................
dmi.board.name: S3420GP
dmi.board.vendor: Intel Corporation
dmi.board.version: E51976-405
dmi.chassis.asset.tag: ....................
dmi.chassis.type: 17
dmi.chassis.vendor: ..............................
dmi.chassis.version: ..................
dmi.modalias: dmi:bvnIntelCorp.:bvrS3420GP.86B.01.00.0042.042920102218:bd04/29/2010:svnIntelCorporation:pnS3420GP:pvr....................:rvnIntelCorporation:rnS3420GP:rvrE51976-405:cvn..............................:ct17:cvr..................:
dmi.product.name: S3420GP
dmi.product.version: ....................
dmi.sys.vendor: Intel Corporation