I just downloaded the systemback package you mentioned and ran dpkg -I systemback_1.8.402_amd64.deb on it. This shows that it has a Conflicts line saying that it conflicts with live-config, and live-config-systemd
$ dpkg -I systemback_1.8.402_amd64.deb new Debian package, version 2.0. size 956864 bytes: control archive=890 bytes. 1511 bytes, 20 lines control Package: systemback Version: 1.8.402 Architecture: amd64 Maintainer: Xiao Guoan <[email protected]> Installed-Size: 1367 Depends: libc6 (>= 2.14), libqt5core5a (>= 5.5.0), libqt5gui5 (>= 5.0.2) | libqt5gui5-gles (>= 5.0.2), libqt5widgets5 (>= 5.2.0), libstdc++6 (>= 4.1.1), libsystemback (= 1.8.402), libx11-6, casper | live-boot, dosfstools, fonts-freefont-ttf | ttf-freefont, genisoimage, squashfs-tools, syslinux, syslinux (<< 3:5) | isolinux (>> 3:6), syslinux (<< 3:5) | syslinux-common (>> 3:6), syslinux (<< 3:5) | syslinux-utils (>> 3:6), systemback-efiboot-amd64 (= 1.8.402), systemback-scheduler (= 1.8.402), upstart | sysvinit (>= 2.88) | systemd, xterm, zenity | kde-baseapps-bin | kdebase-bin Recommends: grub2-common, grub-efi-amd64-bin, grub-pc-bin, lupin-casper, systemback-cli (= 1.8.402), systemback-locales (= 1.8.402), ttf-ubuntu-font-family Suggests: btrfs-tools, jfsutils, reiserfsprogs, xfsprogs, unionfs-fuse Conflicts: live-config, live-config-systemd Breaks: systemback-gui-common (<< 1.0.0) Replaces: systemback-gui-common (<< 1.0.0) Section: admin Priority: optional Description: Simple system backup and restore application with extra features Systemback makes it easy to create backups of the system and the users configuration files. In case of problems you can easily restore the previous state of the system. There are extra features like system copying, system installation and Live system creation. . This package contain a Qt5 graphical user interface for Systemback.
Version 1.8.5 of systemback from the github repo you mentioned has the same Conflicts line:
$ dpkg -I systemback_1.8.5_amd64.deb ... Package: systemback Version: 1.8.5 Architecture: amd64 Maintainer: Kende Krisztián <[email protected]> ... Conflicts: live-config, live-config-systemd ...
A Conflicts line generally means that the developers or maintainers of a package know that it doesn't work, or doesn't work correctly, if you have either of the conflicting packages installed. Or that it prevents those other packages from working correctly. That there is some incompatibility which they either haven't got around to resolving yet, or which is impossible to resolve.
Ask the devs, and/or read through the changelog, commit history, github issues (both open AND closed), and the original launchpad bug tracker for the package.