In theory, yes.  But I don't know if there is a tool around to do it.

If the packages were in Monticello format, it would simply be a matter
of removing the packages or installing an older version of the packages.

If you want to undo individual changes, though, realize that you can
look at the "versions" of any mothed by using the yellow-button menu,
and then you can select any of the older versions and say "revert" to
that one.  Also, there are various ways to get a list of changes that
have been made recently.  Try different things in the "changes" menu to
see them.

-Lex