imagemagick cannot append svg images

[Imre Péntek]

please find the qrsvg1.svg file attached (created with qrencode)

the command

convert qrsvg1.svg qrsvg1.svg -append output.svg

generates a malformed svg file as its output

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: imagemagick-6.q16 8:6.9.10.23+dfsg-2.1ubuntu11.4
ProcVersionSignature: Ubuntu 5.4.0-89.100-generic 5.4.143
Uname: Linux 5.4.0-89-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.20
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Oct 21 17:30:32 2021
InstallationDate: Installed on 2019-11-23 (698 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=hu_HU.UTF-8
 SHELL=/bin/bash
SourcePackage: imagemagick
UpgradeStatus: Upgraded to focal on 2020-06-03 (505 days ago)