Missed duplicates

[Vrish-B25]

I've 2 data drives with ten-thousands of files, many of them are duplicate however they're in a complete different folder structure.
I'm using CzKawka Gui 8.0.0 to find duplicate files.
However i notice that CzKawka does not find certain duplicates.
Of course i doublechecked using another app that these are 100% binary identical files.
I disabled "Use cache".
What could be the reason for this?

[Vrish-B25]

I found the reason: I only now noticed the "Items Configuration" tab where i can set the minimum size.
These unfound duplicates where small files below the default 16K size.
So i've set the minimum size to 1 byte and now they're detected.
Case solved.

But while i'm here i've this question:
How does CzKawka define 2 files duplicate: Is it only when both file lengths and both hashes are equal?
Or is in case both length and hash is equal also the entire file binary compared to ensure there is no hash collision?