mashls4,
having the same encryption domain on both gateways does not mean that you have access to all ressources internal.
You can define different remote access rules for you two gateways. Meaning FW_Corp has rules only allowing traffic to "VPN DOMAIN 1= NETWORK A + NETWORK B" and FW_NOC has rules only allowing traffic to "PN DOMAIN 2= NETWORK A + NETWORK C"
The let the client only use one gateway at the time you can configures these in the trac_client_1.ttm file.
With these file you control the behaviour of the VPN client.
Hope that's fit your requirements.
Wolfgang
PS.: Be aware you can have a different VPN domain for RemoteAccess and Site2Site VPN.