The macros used in the file path for most ResultListeners will ensure a unique file name is created for every TestPlan run.
For example, the settings below will automatically use a timestamp and verdict to create the report name. The output will look something like:
RampResults-2018-04-25-11-02-02-Pass.csv
Several other macros and environment variables are supported. Please refer to the EditorHelp.chm file located in your TAP install directory for more information.