Welcome to our community, Joan
For what it's worth, my own experience with this is that
RoboHelp tends to add the font family name each time it has been
edited. In this case, perhaps someone had declared that style
initially, then tweaked it and closed the Style editor. Tweaked
again.... and again... finally arriving at what they wanted. So you
might see the name listed repeatedly.
I have seen similar things when editing the Background Image.
The first edit may list ../ImageName.GIF. A later edit changes it
to ../../ImageName.GIF. And after three or four edits it looks
really gnarly. ../../../../ImageName.GIF.
So I personally consider it to be a bug in the way edits to
style sheets are handled.
Cheers... Rick