multi-arch installation of libtspi1 results in conflict

[Martin Kunkel]

When trying to install libtspi1:amd64 and libtspi1:arm64 in parallel, there is a conflict reported.
This blocks cross-compiling from amd64 to arm64.

root@5ac7025c9e9b:/# apt install libtspi1:arm64 libtspi1
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
libtspi1 is already the newest version (0.3.15-0.2).
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libtspi1 : Conflicts: libtspi1:arm64 but 0.3.15-0.2 is to be installed
 libtspi1:arm64 : Conflicts: libtspi1 but 0.3.15-0.2 is to be installed
E: Unable to correct problems, you have held broken packages.

I assume the problem might be caused by missing
   Multi-Arch: same
in the properties of libtspi1 in the control file of the package.

Environment:
Description: Ubuntu 22.04.2 LTS
Release: 22.04

Package versions:
root@5ac7025c9e9b:/# apt policy libtspi1
libtspi1:
  Installed: 0.3.15-0.2
  Candidate: 0.3.15-0.2
  Version table:
 *** 0.3.15-0.2 500
        500 http://archive.ubuntu.com/ubuntu jammy/universe amd64 Packages
        100 /var/lib/dpkg/status
root@5ac7025c9e9b:/# apt policy libtspi1:arm64
libtspi1:arm64:
  Installed: (none)
  Candidate: 0.3.15-0.2
  Version table:
     0.3.15-0.2 500
        500 http://ports.ubuntu.com/ubuntu-ports jammy/universe arm64 Packages