It is as I thought:

The following NEW packages will be installed
dmsetup kernel-diablo-modules-dmloop libdevmapper1.02.1
The following packages will be upgraded:
easy-chroot
1 upgraded, 3 newly installed, 0 to remove and 116 not upgraded.
Need to get 124kB/246kB of archives.
After unpacking 381kB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
libdevmapper1.02.1 dmsetup kernel-diablo-modules-dmloop easy-chroot
Install these packages without verification [y/N]? y
Get: 1 http://repository.maemo.org diablo/free easy-chroot 0.2.2-1diablo1 [124kB]Fetched 124kB in 2s (53.2kB/s)
Selecting previously deselected package libdevmapper1.02.1.
(Reading database ... 26889 files and directories currently installed.)
Unpacking libdevmapper1.02.1 (from .../libdevmapper1.02.1_2%3a1.02.27-maemo1_armel.deb) ...
dpkg: error processing /var/cache/apt/archives/libdevmapper1.02.1_2%3a1.02.27-maemo1_armel.deb (--unpack):
trying to overwrite `/lib/libdevmapper.so.1.02.1', which is also in package easy-chroot
Selecting previously deselected package dmsetup.
Unpacking dmsetup (from .../dmsetup_2%3a1.02.27-maemo1_armel.deb) ...
dpkg: error processing /var/cache/apt/archives/dmsetup_2%3a1.02.27-maemo1_armel.deb (--unpack):
trying to overwrite `/sbin/dmsetup', which is also in package easy-chroot
Selecting previously deselected package kernel-diablo-modules-dmloop.
Unpacking kernel-diablo-modules-dmloop (from .../kernel-diablo-modules-dmloop_2.6.21-200842maemo1.3_armel.deb) ...
Preparing to replace easy-chroot 0.1.9 (using .../easy-chroot_0.2.2-1diablo1_armel.deb) ...
Unpacking replacement easy-chroot ...
Errors were encountered while processing:
/var/cache/apt/archives/libdevmapper1.02.1_2%3a1.02.27-maemo1_armel.deb
/var/cache/apt/archives/dmsetup_2%3a1.02.27-maemo1_armel.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)