It seems you can save with an optional name:

Manual says: SaveDocument Explanation Save an existing Poser document. Takes an optional file name as argument.

Arguments Enter a valid path to save the file to that location/filename. If you do not specify an argument, the file will be saved in its current path with its current name.

Syntax SaveDocument({ filePath})

Example poser.SaveDocument(“C:My DocumentsPoser Stuffmyscene2.pz3”)