No matter what, you'll get just one image, dimmer than usual.

It wont act as two lenses because the two pieces lie one-above-the-other.For them to behave as independent leses, you need to have two different optic centres.

Half a convex lens doesnt converge light,right?

Its just that the few rays which passed through the optic centre will now be absent.

A similar thing is a worked example in NCERT class X textbook if I remember correctly...something to do with a zebra..