So no matter what your InDesign file is called, it names the .ps something else completely? For instance, the .ps is named "brochure.ps" (or whatever) every time, no matter what document you are printing?
I haven't seen that before, though it's been years since I printed to a PostScript file.
I just did an experiment where I created a Print Preset that creates a PostScript file (device independent), then used it to create .ps files from 2 different ID documents and it named them accurately "filename.indd.ps".