When multiple DocBoss users are assigned an action on the same card, their review can be completed simultaneously without concern of overwriting and/or losing another's work.
If two (or more) users are reviewing a file at the same time and markups are being applied, all markups will be saved. However, in order to see markups applied by another user, the card will need to be closed and re-opened for those markups to be visible. For example, the user could save their changes (via "Save for later" button) and re-open the card via Outstanding Actions.
Note: Markups applied to a file can be edited and/or deleted other users, and these changes are not recorded. This is in an effort to allow for flexibility during the review process (with markups only becoming "locked into the file" at the time of submittal).