The engineering mockup of the North American A3J Vigilante had two verticals. It went into production with the single center fin.
Presumably the two verticals were intended to ease below-deck storage, which the single fin adapted to by folding down.
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It interesting to note that almost all high-speed planes since the A3J of its mockup configuration... large rectangular inlets, lots of wing, twin verticals... F-15, F-14, MiG-25,MiG -31, Sukhois... all follow that lead.