several heads of a branch?

In
http://matt.eifelle.com/2010/09/21/bazaar-git-or-mercurial-some-thoughts/

the poster concluded his opinion on HG:
I tried MErcurial because it allows you to change the current branch you’re working with, and also you can have several heads for your branch (they are called unnamed branches I think). Although this adds a level of complecity, I don’t always want to create a new branch for a small task (like I’ve created a branch for my contractors, but I’ve added some modifications to their code, I won’t create a new branch for that), but I want to keep things in separate branches.

Is this also possible with BZR?