How to identify issues that are having system generated start date value

[Sai Grandhi]

We are having a field called 'Start Date'. This field is used to note the date when the issue is moved to WIP. We configured a post function on the workflow transition to WIP such a way that system will automatically enter the date of the day when the issue moves to WIP. 

Some of the users are not aware of this and they manually filled the Start Date field before the issue was moved to WIP. System will not update the field if there is a value already in the Start Date field. We would like to know if there is any way to figure out all the issues that were manually filled by user vs issues that are having system generated value for start date field.

We can check in the history of each issue and see when the start date was updated but we are looking for any JQL or other way to get the list of all the issues with system generated start date value or user entered value.