The table ODF_OBJECT_COPY_FLAT stores the source and destination project's internal IDs and keep a history of each unique combination of the source and destination projects.
Here is a query to identify the internal ID of a template from which a project has been created or copied from. This does not include task copy.
select templ.code copiedFrom, copied.code copiedTo, flat.created_by copiedBy, flat.created_date copiedDate
from odf_object_copy_flat flat, inv_investments templ, inv_investments copied
where flat.src_object_id = templ.id
and flat.object_code = 'project'
and flat.object_id = copied.id
Example result from a project 'copied1' created from a template 'csk.majorIT', followed by a copy project done from template 'test_template', again from template 'csk.infrastructure', and again from template 'test_template':