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Note that PreRelease is set to "(same as duration)" by default for some objects

This means the Text object (Stim) in the screenshot above has a duration of 1000 milliseconds so also a PreRelease of a 1000 milliseconds. This then means that AMS markers 2 is send directly after marker 1. Instead of 1000 milliseconds later as you would probably want to indicate the start of the Feedback object.

from the PSTNET.com website:

Using PreRelease allows the currently displayed stimulus to lend time to the following stimulus so that following stimulus can perform setup activities (e.g., reading data from a disk, getting the image ready in memory). Thus, when the second stimulus is scheduled to display, it is simply copied to the screen and any delay caused by setup activities is eliminated. 

As you can see in the bottom situation PreReleasing time from Stim also immediately sends marker 2 after marker 1.