Let's see now...  If I had a purple piano bench, and there were no other
purple piano benches, it would be unique.  If it also had a player-pumping
support mechanism seen in no other piano benches, especially the purple
ones, then I think it might fairly be said it was twice as unique as
I had first thought...  Don't listen to me, I'm being silly!

Seriously, though, one of your examples is fully approved: the x number
of "unique replies."  That is not a violation of the rules for unique,
it's just a technical or jargon use to indicate unconnected independent
events.

Jim Katz