Unlike the ASA there is not an automatic feature to keep the configuration in sync across the 2 IPS SSMs.
You can use the copy command to copy the configuration from one sensor to an ftp/scp server.
Then use the copy command on the second sensor to copy the configuration onto the second sensor. During the copy it will ask whether or not to change the sensor’s IP to what is in the configuration file. You will need to tell it to NOT change the sensor’s IP, otherwise you would wind up with 2 SSMs with the same IP and have trouble connecting to them.
Another option is to use CSM. CSM has configuration that applies to single sensors, but also has group configuration that can be applied across multiple sensors.
If you used the group configuration, then you could make a single change at the group configuration and apply it across all sensors in the group (you would place your 2 SSMs into the same group).
These two option synchronize the configuration data between two IPS systems one more automated than the other. Hope this helps.