If you execute the following code:

            stepRequest1 = erm.createStepRequest(mainThread,
                                                StepRequest.STEP_LINE,
                                                StepRequest.STEP_OVER);
            stepRequest2 = erm.createStepRequest(mainThread,
                                                StepRequest.STEP_LINE,
                                                StepRequest.STEP_OVER);
            stepRequest1.enable();
            stepRequest2.enable();

You would expect that the event handler would receive two StepEvents, one for each request. That is the way other EventRequest works. It turns out you'll only receive one StepEvent, and it will be for the 2nd (last) StepRequest that is enabled.

The 2nd issue is that if you disable either StepRequest, both of them get disabled.