It is about 200m westsouthwest of the main population on the same ridge line. I count 12 leaves in the rosette. PlantNet says up to 10 leaves (http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Pterostylis~hamata); Jones et al Field guide says up to 12 leaves.
Based on the fact it was on an exposed and very rock slope, I don't think there are any other orchid species known to occur in Canberra that would grow in such "terrible" conditions.