advantages of dual quad intake?

what are the advantages and drawbacks of having a dual quad intake over a single carb intake?

In this day and age, there is really little advantage of a dual quad (or tri-power for that matter) manifold over a properly designed and carburated single four barrel unit.

Generally speaking factory multiple carb intakes became popular in the mid 50's on high preformance engines and actually could make substantially more power at that time but it wasn't primarly due to the design of the intake. The main reason that the dual quad and Tri-Power units came into existance was based on carburator technolgy. At that point in time nobody was really making carburators that could flow enough to to keep up with the "new" high preformance engines. The quick and cheap fix at the time was to add variations of existing carburators to a new manifold rather than retool for a new carb (an intake manifold is generally a single componet while a carb is made up of a whole bunch of little parts).

As Detroit and the aftermarket started catching up with better carbs the need for multiple carbs really became less, however by that time the public had been sold on the more is better thing, and dual quads and tri-power were carried over past where it was really necessary (into the early 70s for Chrysler).

A dual quad intake is generally more expensive than a single quad unit, plus the added costs of a second carb linkage, air cleaner(s) etc for really no noticable preformance gains over a well selected single 4BBL unit.

I personally enjoy the multiple carb units from an image standpoint and the challenge of dialing the unit in (I usually set up my own carbs and build my own linkage), but from a purely practical standpoint the single 4BBL is the way to go.

wouldn't the multiple carbs allow for better fuel distribution?

Unless you are really twisting the motor, about the only advantage you get is the wow factor when you open the hood. Like Streets said, you won't have to worry about what to do in your spare time, you can sync and tune the carbs.