Comment 1 for bug 44490

IMHO, it can be considered as a bug.
The only way to move two connected windows (not only with update-manager, but also with synaptic) is to mark the active one as 'always in the visible work area', change desk, then mark the visible window as 'only in this work area' - don't know if the real English words are like that, I use Ubuntu with Italian l10n).