I modified the sample project created by tns create and tried to bind multiple events on the button.

<Button text="TAP ME" tap="{{ tapAction }}" doubleTap="{{ doubleTapAction }}" cssClass="border-test font-test" />

But only tapAction can be fired.
However if I don't use data binding syntax (of course I have to move functions to main-page.js instead):

<Button text="TAP ME" tap="tapAction" doubleTap="doubleTapAction" cssClass="border-test font-test" />

Then both tapAction and doubleTapAction can be fired properly.
Is there something I'm missing?