No.
Not without something like Brawler's Flurry or Sohei Weapon Training.
It is only a double weapon for the cost of upgrading the sword and the pistol.
The TWF rules say "If you wield a second weapon in your off hand", and you don't do that when using a sword-cane pistol (neither the second weapon part, nor the off-hand part). It's one weapon. Having multiple attak modes is irrelevant, unless the weapon is specifically made to allow TWF (represented by the double weapon feature). For comparison, a starknife has four blades, doesn't mean it can attack four targets...
In this case, the ONLY way to use both modes in one round would be to use your regular iterative attacks. If you have +10/+5, you can make a pistol shot at +10 and a sword cane attack at +5, and that against 2 targets.
IIRC, you can use your regular iterative bonus to attack with multiple weapons WITHOUT the TWF rules, and that against as many opponents within reach.
At this point, you could TWF the sword cane (with the pistol) WITH its scabbard, be improved or combat-fitted.