duplicates of parts of a line in list

[Jim sims]

I have a list of items such as in example 1 shown below.

I want to record how many are the same but only the same by char 1 to 2 and
char 6 to 7 then place that number of duplicates after each line, as in the
second example list.

Any ideas for doing this?

Thanks,
sims
---

LIST 1

08:00_d3_180_Monica_pink

10:45_d2_90_Mary_orange

10:00_d2_90_Mary_orange

10:15_d2_90_Mary_orange

10:30_d2_90_Mary_orange

10:00_d2_90_Mary_orange

10:00_d2_90_Mary_orange

12:30_d5_45_Mary_blue

12:45_d5_45_Mary_blue

12:60_d5_45_Mary_blue

LIST 2

08:00_d3_180_Monica_pink_1

10:45_d2_90_Mary_orange_3

10:00_d2_90_Mary_orange_3

10:15_d2_90_Mary_orange_3

10:30_d6_90_Mary_orange_2

10:00_d6_90_Mary_orange_2

10:00_d3_90_Mary_orange_1

12:30_d5_45_Mary_blue_3

12:45_d5_45_Mary_blue_3

12:60_d5_45_Mary_blue_3