Hi Gareth
Inaport has very powerful matching capabilities, but does not support currently merge-purge operations. To do a merge-purge, the surviving company must be identified, then all the child records from any non-surviving company must be moved to the survivor, and finally the non-survivor deleted. There must also be business rules for merging the data in the company records.
It is possible to use Inaport to import the CRM database into itself, and "tag" any company records that match. However, this process can be quite tricky, and you then have to use the CRM user interface to manually merge-purge the resulting sets of companies.
A better approach is be to set up a clean CRM database and import the old database into it, using Inaport matching facilities and the "create or update" table operation on Company to prevent duplicates as the data is imported. This will also provide a clean way to attach child records to the surviving company record.
Regards
David