Look at the linked accounts and their labels. A record can hold one verified account per platform. Other accounts can be listed as Related Accounts, but those are not verified.
For software, confirmed account links appear in sameAs. Handles found only through public sources appear as identifier values. Do not treat those as confirmed account links.
The same handle can belong to different people on different platforms. Check the platform and account links, not just the text of a handle. If you search by handle, treat the results as possible matches to check.