Yes, TimesTen supports the "Active-Active" replication. All updates will be transferred between two instances but you should avoid a situation with updating the same row at the same time. Timesten also has a conflict detection mechanism.
For more information please see the documentation (http://docs.oracle.com/cd/E21901_01/doc/timesten.1122/e21635/design.htm#CACDEIBF)
If you are using TimesTen to cache Oracle database tables (via TimesTen Cache Group), the supported Replication configuration for HA is Active-Standby Pair with optional subscribers for readonly. In A/S Pair configuration, updates are allowed only on the Active and Standby can be used for reads.
Can you expand on your use-case and what you meant by active-active? What are your high availability requirements?