How many ways are there to layout 2 out 3 desirable perks over 3 perk spots?

1 2 ?
1 ? 2
? 1 2
1 3 ?
1 ? 3
? 1 3

2 1 ?
2 ? 1
? 2 1
2 3 ?
2 ? 3
? 2 3

3 1 ?
3 ? 1
? 3 1
3 2 ?
3 ? 2
? 3 2

18 ways

for each row there's 28 perks left to fill the question mark

between rows with question marks there will be duplicates,
  1 2 3 is matched by  1 2 ? and 1 ? 3 and ? 2 3
    but 1 2 4 is only matched by 1 2 ?
        1 4 3 is only matched by 1 ? 3
        4 2 3 is only matched by ? 2 3
  so duplicates only happen when the question mark is filled by one of the accounted for perks

there won't be so many duplicates so let's say there's 18 * 28 ways to lay out (2 out of 3) desirable perks

there's 30*29*28 possible ways to fill 3 spots using 30 perks
chance to roll 2 out 3 desirable perks in a single roll = 18*28 / 30*29*28 = 0,0207