CountIf Question

[hodkd]

I have a spread sheet to keep track of work schedules and I use a Capital letter to show a day 12 hour shift and a small letter to show a night 12 hour shift. I set up a countif formula to let me know if there were at least two of the same letters in the same day. That works okay but it counts them the same if they are both capitals or small letters. Would there be some way for the formula to count them only if there is both a small and capital letter and not if there are only small or capital letters?

Jan
1 2 3 4
H H H h
h h h h
2 2 2 2 This is where the countif formula is and I would like it to not count unless there is both a capital and small letter not two of each.

See attached sheet for a better sample