Cribbage counting a hand
You can't count it as 4 double runs, as that double counts a number of elements.  It is 4 runs of 3

8H, 9H, 10C

8H, 9D, 10C

8D, 9H, 10C

8D, 9D, 10C

and 2 pairs (the 8s and 9s) for a total of 16.