A dual digital signature is a transaction control that requires two authorized people to approve the same action before it can proceed. In financial systems, this is a stronger form of segregation of duties: one user may prepare a payment, but a second user must digitally confirm it. The second approval is typically recorded in the system audit trail, making the control both enforceable and reviewable.
This matters because many insider frauds do not rely on malware; they abuse legitimate access. A dual-signature rule can stop a payroll change, reimbursement, or bank transfer even when one trusted user has the right permissions. Defenders use it for high-value or sensitive workflows to reduce errors, limit abuse, and create evidence for later investigation. If approvals can be bypassed, the control is only procedural, not security.