Can DICOMScope generate GSPS which specifies different rotation/flip for different images?
DICOMscope is quite limited when it comes to multiple images in a presentation state. This is especially true for the creation of presentation state objects. So I guess, the answer is no.
The restriction to one image at a time -- apart from a few exceptions -- was a design decision and is based on the requirements which had to be fulfilled for the reference implementation (sponsored by the NEMA Committee for the Advancement of DICOM back in 1998/99).