printing from InDesign CS2 with InRip Separation mode procudes multipage PS

[Lionel]

Hi every one

Working on Mac OSX 10.4.11 (intel) with Adobe InDesign CS2 (4.0.5)
we print a 5 colors (C+M+Y+B+Spot) single page *with InRip Separation mode*

all we get is a multi-page PostScript file : one page for each color (like it would have been preseparated)
while we were expecting a one page PS file

do you have experiment same result using InRip Separation mode?

Although on one particular mac (same OS and software versions, intel)
we do get a single page PS file

we can't figure out why....