Cisco ASA Active-Active

With Active/Active failover, two ASAs can operate in a redundant fashion. If one fails, the other one can take over all ASA operations. In such an arrangement, both ASAs can forward traffic.

In contrast, Active/Standby mode allows only one ASA to forward traffic, while the other one remains idle until the first one fails.

Active/Active failover is only available to ASAs in multiple context mode.

https://www.cisco.com/c/en/us/td/docs/security/asa/asa98/configuration/general/asa-98-general-config/ha-failover.html

https://www.cisco.com/c/en/us/td/docs/security/asa/asa84/configuration/guide/asa_84_cli_config/ha_active_active.html