Additional Main Process in each diagram

When I create new diagram, Bizagi Modeler automatically adds process called "Main Process" to this diagram. In Bizagi Modeler, this second process (Main Process) is not visible but when I export diagram to .bpmn in this file I can find two processes: one which corresponds to diagram which I created and second one, Main Process which practically empty (it only contains pool):

<process id="Id_b3bf6b60-b360-4d63-9dd7-ae83ffd9f90a" name="Main Process">

<documentation />

</process>

and the second entry in collaboration section:

<participant id="Id_4902dbc7-3c84-428f-9524-7b125f317e99" name="Main Process" processRef="Id_b3bf6b60-b360-4d63-9dd7-ae83ffd9f90a">

<extensionElements>

<bizagi:BizagiExtensions xmlns:bizagi="http://www.bizagi.com/bpmn20">;

<bizagi:BizagiProperties>

<bizagi:BizagiProperty name="bgColor" value="White" />

<bizagi:BizagiProperty name="borderColor" value="Black" />

<bizagi:BizagiProperty name="isMainParticipant" />

</bizagi:BizagiProperties>

</bizagi:BizagiExtensions>

</extensionElements>

</participant>

The main problem is when I try to import bpmn file to other BPMN Tools because they read that two section and each time two processes/pools appear (my process and Main Process) and always I need to delete Main Process manually. Strange is also, that shape of that Main Process is different (and always the same) than diagram created by me. Why does Bizagi add this Main Process to each diagram? What is the purpose of that Main Process? How can I delete that Main Process directly from Bizagi before export diagram to .bpmn file?