Dual-beam x-ray tomography systems are paving the way for new experimental procedures, such as multi-resolution and multi-energy imaging, where synchronous acquisitions are essential. However, in such systems, cross-detector scatter between the detecting devices can occur as the two beamlines operate simultaneously. This paper proposes a new affine image transformation model of each projection to correct for these cross-detector scatter issues. A toy tomography test case is presented to assess the feasibility and performance of the proposed correction method.