Which results will be returned with the following Google search query? site:target.com site:Marketing.target.com accounting

This choice implies results are limited only to Marketing.target.com within target.com, which is simply Marketing.target.com itself - the opposite effect of what the dual site: operator produces.

The site: operator is a domain-filter directive, not a keyword inclusion rule; Google does not treat site: values as words to match in content.

Two site: operators do not produce a union of both domains; Google does not return results from both target.com and Marketing.target.com simultaneously with this syntax.

When two site: operators are used where one target is a subdomain of the other (site:target.com site:Marketing.target.com), Google interprets the conflict by returning results from the parent domain (target.com) that exclude the specified subdomain (Marketing.target.com). This means the query returns pages matching 'accounting' on target.com while filtering out any pages hosted on Marketing.target.com.