According to NCM 7.8 release notes, multiple context from ASA devices are handled individually.
"Support for multiple VDCs
Cisco Nexus series switches provide support for virtual device contexts (VDCs). Each VDC runs as a separate logical entity within the switch.
To add a Cisco Nexus device with multiple VDCs to NCM, first add the admin VDC using its IP address. All other VDCs will be automatically discovered, and you can add each VDC as a separate node. You can then configure NCM to back up and restore configurations for all VDCs accessible via SSH or Telnet from the NCM server."