HubSpot import duplicate contacts / duplicate email

HubSpot uses Email as a key contact identifier. If two CSV rows use the same email address, an import can update or dedupe against the same contact instead of creating two separate people.

Blank Email values are a different risk. HubSpot can still create a contact from First name or Last name, but email-keyed matching, updates, and duplicate-safe imports will not apply to that row.

Duplicate contacts often come from merged exports, repeated form submissions, CRM-to-spreadsheet round trips, or copied rows that were not deduped before import. Even when the rows look slightly different, the same email can make HubSpot treat them as the same contact identity.

• Case changes such as ALEX@example.com vs alex@example.com should be reviewed as duplicates.
• Extra spaces around an email can hide a duplicate in a spreadsheet view.
• Fully duplicate rows usually mean the source export was appended or copied twice.
• Name-only rows can create contacts, but they are harder to match safely later.

1. Sort or filter by Email after trimming obvious leading and trailing spaces.
2. Choose which row is the source of truth when the same email appears more than once.
3. Merge useful field values into one row instead of importing conflicting duplicates.
4. Review rows with First name or Last name but no Email before using them for updates.
5. Keep a backup of the original export before deleting duplicate rows.

ReadyCSV flags repeated Email values as duplicate_email warnings. The comparison is case-insensitive and ignores whitespace inside the email value, so Alex@example.com and alex@example.com are reviewed as the same email.

ReadyCSV also flags fully repeated rows as duplicate_row warnings, and it flags rows with a blank Email but present First name or Last name as email_recommended_for_dedup warnings. These are review signals, not automatic deletes or HubSpot-side merge actions.

For broader setup, start with how to format a CSV for HubSpot import, then review the invalid email guide and missing required fields guide.