CIA 6526 chip used in Commodore 64 is capable of controlling two separate joystick buttons. But the second button should be connected through paddle pot input. This option was not popular till the release of Commodore 64GS (Game System). C64GS came with Cheetah Annihilator joysticks that officially has two separate buttons.
Apparently, several two button game have been released after C64GS. But I couldn't find the names. So what are the two button C64 Games?