Yes the only time I have seen it is with a single breasted vest, otherwise I think visually it would be too much and would be rather impractical and uncomfortable with so many buttons and overlap of cloth.
I think you have to look at the synergy between vest and coat on every suit although for me its not something that is agonized over, its more intuitive. With my DB I went for a slightly higher buttoning vest and kept the button placement and break on the coat fairly classic. The rationale being for the coat to be open when worn with the vest, the vest makes it look put together but with the suit being linen and the coat being open you end up with a looser fitting and layered garment which is good for hot climates.
Would any adjustments need to be made if it were a flannel double breasted suit? Seems like there would be a lot of fabric in there to keep a nice slim silhouette. Or do you advise against it with certain fabrics. Every time I put on my two piece suits, I pretty much always wish they were three piece. Maybe we should make that a rule for me from now on.