What is the recommended way to build an apt mirror with multiple versions of packages?

We have a local apt mirror built with apt-mirror and it's working nicely, but since it considers valid only the latest version of every package, if there's the need to downgrade one of them (because of a regression or whatever) we can't rollback to the previous one, we can only go back to the first version available. For example, we are having a problem with Thunderbird 24.5.0 and we'd like to go back to 24.4.0, but: $ apt-cache show thunderbird | grep Version Version: 1:24.5.0+build1-0ubuntu0.12.04.1 Version: 11.0.1+build1-0ubuntu2 What is the recommended way to build an apt mirror that keeps more versions of the same package available?