I think it looks ugly.
I take a Think Tank Urban Disguise anytime.
And I very rarely use two bodies with messenger bags. The bag swell up to much and its heavy. If I do I use shoulder bags like Domke F1 (with the capacity yet remains small).
Also many bags advertisements they put two bodies, but plastic consumer bodies without grips. They put lenses, but smaller prime lens without hood. In real world usage, loading two gripped pro bodies with the big 24-70 zooms with hoods... think you get the idea.
Go backpack or roller for heavy setups.