Hi @softlightdan,
For companies, HubSpot uses the company domain name (the company’s website domain) as a unique identifier. If this unique identifier appears twice or more times in an import file, this causes an error.
If you have several companies with the same company name, e.g. ACME, this wouldn’t cause a problem as long as they have distinct company domain names, e.g. acme.org, acme.com, acme.net. (Should ACME appear several times with the same domain name, that’s a sign that these rows are actually duplicates since they have the same unique identifier.)
Hope this helps!