Can you use a unique ID other than name for merging on import?

Is there a way to use an ID of some sort as the unique identifier for a company, rather than the name? I have different companies with the same name, and so if I'm doing an import to update company data I need some way to tell it which of the same-named companies to update.

To date my workaround is to embed a unique ID into the company name ("Company (ID)") but it's kind of kludgy