Looks like you are on the right track. Now you need to apply the insert multiple records server behavior instead of the insert server behavior.
Before that you will need to add a hidden form element directly before the checkbox like:
<input name="HidField<?php echo $RepeatSelectionCounter_1; ?>" type="hidden" value="1" />
The reason why is that the multiple insert server behavior depends on at least one element from the form existing in order to do an insert and an unchecked checkbox acts as if no values are in the form at all and would break out of the loop.
Anyway... remove the insert server behavior and apply the insert multiple server behavior and see how it works for you from there.