People told me in the past that they were not able to use the Matrix Eater animation transfer/import capabilities to handle camera animation to allow one model to have an Alternate camera similar to how you do. Did you create your DualCam using automation or did you have to manually hand edit the camera to be a copy of the Siege Engine in the alternate case and then do camera translations and rotations to match the Siege Golem in the base case?
Edit:
p.s. don't use Matrix Eater, use
Retera Model Studio. The Retera Model Studio should be fully backwards compatible and have a superset of all features that Matrix Eater ever had in 95% of all cases.