Is there a double fulfillment for the Oracle against Damascus? As my commentary, Believers Commentary by Wm. MacDonald, says the one in Is. 17 has been fulfilled. He says Damascus was destroyed by the Assyrian armies in 732 BC and Samaria fell ten years later. I was surprised when I read this as you hear a lot about Damascus being destroyed, ala Isaiah 17.
Damascus was conquered by the Assyrians as your commentary states. But it was never destroyed to a point where it was no longer a city and became a heap of ruins in the manner Isaiah 17:1 describes. In fact Damascus makes the claim of being the world’s oldest continuously inhabited city. Isaiah 17 awaits a future fulfillment.