It is not really possible to 'click twice' using capacitive touch screen, change the trigger action to long click/press may solve this issue. Reproducible: Always
It should be possible to click twice using a touch screen. You might need to increase the settings in kcmshell4 mouse > Advanced. For input devices that really do not allow double clicking (for whatever reason), the input layer for those devices should do the emulation. You cannot expect every application to add special code for each input device that wants to emulate a mouse.