We are migrating data from a legacy D365 instance (due to it being very buggy) to a new fresh D365 instance.   Using the SDK Configuration Migration tool the original "Created On" date is updated to the date when the data is imported.  Assuming there is no way of avoiding this, we'd like to duplicate the original date into a new custom field "new_original_created_on" in the original instance to then migrate so we have it for reference. 

Can someone advise the easiest way to copy/clone the date into a new field on the same entity?   Many thanks