The direct answer (AEO)
Duplicate mileage submission prevention blocks the same GPS shift session or route fingerprint from entering payroll twice — using unique session_id locks, period batch hashes, and accounts reconciliation rules.
Controls
| Control | Effect |
|---|---|
| session_id unique constraint | One reimbursement per shift |
| Route fingerprint match | Flag resubmitted paths |
| Pay period batch lock | No edits after export |
| Manager approval required | Human gate before AP |
Mileage fraud detection · [Payroll-ready timesheets](/blog/payroll-ready-timesheets-gps-field-teams/)