Even after the second bomb, some Japan's military leadership wanted to keep fighting.
> The Kyūjō incident (宮城事件, Kyūjō Jiken) was an attempted military coup d'état in the Empire of Japan at the end of the Second World War. It happened on the night of 14–15 August 1945, just before the announcement of Japan's surrender to the Allies. The coup was attempted by the Staff Office of the Ministry of War of Japan and many from the Imperial Guard to stop the move to surrender.
> The officers murdered Lieutenant General Takeshi Mori of the First Imperial Guards Division and attempted to counterfeit an order to the effect of occupying the Tokyo Imperial Palace (Kyūjō). They attempted to place the Emperor under house arrest, using the 2nd Brigade Imperial Guard Infantry. They failed to persuade the Eastern District Army and the high command of the Imperial Japanese Army to move forward with the action. Due to their failure to convince the remaining army to oust the Imperial House of Japan, they performed ritual suicide. As a result, the communiqué of the intent for a Japanese surrender continued as planned.
> The Kyūjō incident (宮城事件, Kyūjō Jiken) was an attempted military coup d'état in the Empire of Japan at the end of the Second World War. It happened on the night of 14–15 August 1945, just before the announcement of Japan's surrender to the Allies. The coup was attempted by the Staff Office of the Ministry of War of Japan and many from the Imperial Guard to stop the move to surrender.
> The officers murdered Lieutenant General Takeshi Mori of the First Imperial Guards Division and attempted to counterfeit an order to the effect of occupying the Tokyo Imperial Palace (Kyūjō). They attempted to place the Emperor under house arrest, using the 2nd Brigade Imperial Guard Infantry. They failed to persuade the Eastern District Army and the high command of the Imperial Japanese Army to move forward with the action. Due to their failure to convince the remaining army to oust the Imperial House of Japan, they performed ritual suicide. As a result, the communiqué of the intent for a Japanese surrender continued as planned.
https://en.wikipedia.org/wiki/Ky%C5%ABj%C5%8D_incident
Would resistance to surrender have found more support if only a single bomb had been dropped? We will never know.