Yes, you can dual-attack next round.
Zangua's axe seems to bounce right off the construct's flank. Suddenly besieged from all sides, the Implacable thrusts back at Zangua with the butt end of its catchpole, then brings the blade end in a wide arc down onto Everil...
Edit: Zangua lunges away from the thrust of the bronze pole, but Everil is not so quick to react, and the blade slices into his right shoulder. Everil lets out a sharp whine of pain as the blood coming out of his shoulder seems to thicken and clot within seconds, clinging to his fur like strawberry preserves...
Felor, Leth, Mordred, Shamush, you're up.
Rolls
The Implacable's butt-end catchpole attack vs Zangua - (1d20+9)
(1) + 9 = 10
Damage, if applicable - (1d6+5)
(6) + 5 = 11
The Implacable's blade-end catchpole attack vs Everil - (1d20+9)
(6) + 9 = 15
Damage, if applicable - (1d10+5)
(2) + 5 = 7
Everil CON saving throw vs poison - (1d20+2)
(3) + 2 = 5
Everil additional poison damage - (2d4)
(41) = 5