是的，Windows将默认启动一个新实例;但是，您可以控制此行为。在控制面板中，转到任务计划程序。查找任何时间计划任务，右键单击/属性，然后选择设置选项卡。在底部，您会看到一个名为如果任务已在运行，则应用以下规则的选项。您可以选择不启动新实例，并行运行新实例，对新实例排队，或停止现有实例。你想要的第一选择。 Windows任务计划程序API 提供相同的功能。

Yes, Windows will start a new instance by default; however, you can control that behavior. In Control Panel, go to Task Scheduler. Find any time-scheduled task and right click/Properties, then choose the Settings tab. At the bottom, you'll see an option named "If the task is already running, then the following rule applies." You can choose to not start a new instance, run a new instance in parallel, queue a new instance, or stop the existing instance. You want the first choice. The Windows Task Scheduler API provides the same functionality.