sensors docs: clarify run_key behavior in a single sensor evaluation

docs/content/concepts/partitions-schedules-sensors/sensors.mdx

@@ -127,6 +127,8 @@ In the example, a <PyObject object="RunRequest"/> is requested for each file dur
 
 Run keys allow you to write sensor evaluation functions that declaratively describe what runs should exist, and helps you avoid the need for more complex logic that manages state. However, when dealing with high-volume external events, some state-tracking optimizations might be necessary.
 
+NOTE: if you yield multiple <PyObject object="RunRequest"/> with the same `run_key` in the same sensor evaluation, dagster will not skip any of them. That is, all `RunRequests` in a single sensor evaluation will be launched (even if the run key is the same on some or all of them).
+
 ### Sensor optimizations using cursors
 
 When writing a sensor that deals with high-volume events, it might not be feasible to yield a <PyObject object="RunRequest"/> during every sensor evaluation. For example, you may have an `s3` storage bucket that contains thousands of files.