Hi!
I'm afraid what you want is not possible, or put it another way, it's
not possible to get what you want and get sane results at the same
time. The reference counting code uses the package version of each
Multi-Arch:same instance to know when it can replace files or when the
packages are getting in sync and as such need to be exactly the same.
If this was a matter of different file contents that needed to be
overwritten, that would be fine, because the configure check that
guarantees that all instances have the same version would somehow
mitigate such disasters.
But if we had such force option (to disable the version sync check at
configure time), then you'd need to use it all the time, as long as
you have such packages with diverging versions, and then dpkg would be
unable to tell when it should replace or not the reference counted
files when unpacking multiple Multi-Arch:same instances on
upgrades/downgrades for example. I assume apt would also need an
option to override that, or it might get really unhappy.
I will probably add it anyway, because dpkg --force options have
historically pretty much allowed to destroy your own system, but just
wanted to mention the (possibly) unexpected consequences.
Thanks,
Guillem