> Each 10GB chunk of your database volume is replicated six ways, across three Availability Zones. Amazon Aurora storage is fault-tolerant, transparently handling the loss of up to two copies of data without affecting database write availability and up to three copies without affecting read availability. Amazon Aurora storage is also self-healing. Data blocks and disks are continuously scanned for errors and replaced automatically.

This blurs the lines a bit - the DB engine itself isn't doing the master-master replication, but the underlying storage engine is handling that. Your transactions are effectively running with synchronous replicas as if the system is master-master, but the engine itself is not. So you get the data protection guarantees from a master-master system, but not the availability.