Add a recommendation to the data panel to clean up casing differences in a column similar to the existing spaces clean up recommendation.
Display the recommendation when a column contains values that differ only in casing. When selected, add a transformation that keeps the first encountered casing of a value (don't just lower or upper a column).
Add new column: Rank(Lower([Data])) as [Data (casing rank)]
Calculate and replace original column: First([Data]) OVER ([Data (casing rank)])
Exclude added column [Data (casing rank)]
Thanks for an excellent idea. It's in our direction to add this capability (would probably be the first one) and other data cleansing insights to Spotfire.