There have been many threads on this or topics relating to avast becoming bloated by incorporating the likes of a firewall and an anti-spyware, etc.
The response by many and myself included is I wouldn't want avast to become another bloated all-in-one suite of programs. avast! is relatively light on resources and that is what many like about it. I personally would rather be able to select a program that matches my needs and requirements rather than have that decision made for me.
The saying "Jack of all trades, master of none" comes to mind when I think of software suites. I would rather be able to choose the best in the field for each specialised area.
As far as I'm aware (from previous threads in the forums) Alwil have no plans to include a firewall in avast. There have been threads relating to heuristic scanning (so I would guess a dual engine would fall into the same category), but aside from the email scanner, this too has not received a positive response.
