Beyond NVL

If there's one thing I've ever learned while developing in Oracle, there is always more than one way to solve a problem.

The question is - have you done it in the simplest, most intuitive manner?

That's the bar to set, because it may be you the revisits some code 2, 6, 12 months later...

Recently, I came across some code like this:

CASE
    WHEN NVL(custom_value, normal_value) = normal_value THEN
      NULL
    ELSE
      normal_value
    END AS alt_value

I had a fair idea what it was trying to resolve, but I wasn't sure and I still had to run some scenarios to be sure.
Basically, this was the 2nd of two fields that showed a normal value and a custom value. The first field was simply
NVL(custom_value, normal_value)

The second field should be:
If there is a custom value, show the normal value, otherwise show nothing.