Each measured height value that ends up in the DSM is calculated using one or more stereo models. The number of stereo models that were used for calculating a measurement is usually a good indicator for the accuracy of that measurement, that's why SURE has an option to write the number of stereo models used for each measurement into a 8bit image. The more overlap the input data has, the higher the model count should be. Usually the number of models used will increase towards the center where the overlap is biggest (see the example image below).
The following two images are a DSM (left) and the derived model count image (right). The model count image was scaled so that the value 0 is black (i.e. no measurement for that pixel) and the value 5 is white: