I am taking a dummy dataset where I need to find duplicates for fields A and B. Introduce a column [count] =1.
Do a left join to a second table which only has the DISTINCT key fields. I have taken A and B here. sum(count) will tell you how many times the combination for A and B occurs.
We can see that even though column C is different in the first two rows, it is considering only columns A and B, which you can change to your 5 key fields.
Let me know if this helps!