By "unique" I believe he meant "different" pussy.
Lets say, a guy had sex with 8 different women a month (over a 2 month period).
Does that mean he had sex with 16 women?
So lets say month 1: Was 8 different women including a wife.
Month 2: 3 new women, but had sex with 4 women from month #1 + wife (8 total)
Total different women = 11.
So when I was at my most horndog mode, about half the women I had sex with for the month- were pre-tested pussy.
And of course, we don't usually count our wives (GF) as they are always the playtoy of love.