How to clean an event attendee list and remove duplicate registrations
Clean an attendee list by separating person, registration, ticket, order, and check-in records; normalizing contact fields; and resolving duplicate candidates with event-specific rules. Preserve guest registrations, ticket transfers, cancellations, and multiple valid tickets instead of deleting every repeated email.
Why the obvious method fails
A purchaser may buy several tickets for guests, one attendee may register through two channels, and a transferred ticket can carry the buyer's email. Email duplicate removal alone removes legitimate seats or assigns the wrong person.
Ticket uniqueness and person uniqueness are different
Events need both capacity truth and attendee identity. Keeping ticket and person grains separate allows a group order to retain all seats while still identifying potential duplicate registrations for communication.
Where this usually goes wrong
Do not expose full attendee contact or accessibility information at a public check-in desk. Create purpose-specific, access-controlled exports.
A useful mental model
- Identify order, registration, ticket, attendee, guest, and check-in keys.
- Create comparison-only email and phone fields and protect raw personal data.
- Apply cancellation, transfer, refund, guest, and multi-ticket rules.
- Create eligible tickets, unique attendee estimates, exceptions, and privacy-minimized check-in views.
Patterns that need context
- Registration count and unique attendee count are treated as identical.
- Several guest tickets share the purchaser's email.
- Cancelled or transferred tickets remain eligible for check-in.
From the field · Conference event manager
Prepare one check-in list from ticketing and sponsor CSV files
Public tickets, sponsor guests, speakers, refunds, and ticket transfers arrive from three exports. Some people appear twice, while group bookings use one buyer email for five guests.
Columns used in the example
order_id · ticket_id · registration_id · attendee_name · email · ticket_type · status · checked_in_at
Follow it with your own file
- Map each source to ticket and attendee fields with source history.
- Preserve group tickets and resolve transfers and cancellations.
- Create duplicate-person candidates only when multiple identifiers support them.
- Export a minimum-field eligible check-in list plus a restricted exception file.
Check: Eligible ticket count must reconcile to sold plus complimentary minus refunded/cancelled tickets, each ticket must check in at most once, and person merges must not remove valid seats.
Choose the approach that matches the evidence and repetition
| Approach | When it works | What to verify |
|---|---|---|
| Email duplicate removal | One ticket per verified email | Guests and shared contacts |
| Ticket-level cleanup | Capacity and check-in | Person-level communication |
| Linked ticket/person model | Complex multi-source events | Identity review |
A method you can follow
- Separate entities: Identify order, registration, ticket, attendee, guest, and check-in keys.
- make consistent contacts: Create comparison-only email and phone fields and protect raw personal data.
- Resolve ticket status: Apply cancellation, transfer, refund, guest, and multi-ticket rules.
- Produce operational lists: Create eligible tickets, unique attendee estimates, exceptions, and privacy-minimized check-in views.
Doing these steps in Prepyr
Upload a CSV working copy in Prepyr. Describe the result you need: Clean and remove duplicates from an event attendee or registration spreadsheet. Check the columns selected, preview any proposed changes, and compare the output with the source before applying or exporting it.
Prepyr steps used here: Data cleaning · Verified analysis · Reusable workflows · Reports
What to verify before acting
- Entity grains identified
- Ticket statuses resolved
- Person matches reviewed
- Capacity reconciled
- Check-in fields minimized
A correct, privacy-aware check-in list that preserves every eligible ticket and gives the event team a separate queue for uncertain identities or status conflicts.
Questions readers usually ask next
Should repeated attendee emails be removed?
Not automatically. One buyer may hold several guest tickets or an attendee may have multiple valid registrations.
What fields belong on a check-in list?
Only those needed to identify eligibility and complete check-in, with sensitive details kept in restricted systems.