Starting an already running task runs multiple instances of the same task

When i start a task which has already been started, i end up with more than one running instance of the same task. This happens when say, the user accidentaly clicks the start button after selecting a task which is already running. I have so far not thought of scenarios where we may need to run more than one instance of the same task. Running more than one instance of a task my have not problems for certain types of tasks (expecially those running for short periods), but will definately result into undesired behaviour for others, like the XForms Bluetooth task. If running multiple instances of the same task is the intended behavour, then the user interface should show all these running instances and have a way of letting a user force any to stop.