I have a large spreadsheet that uses merged regions extensively. I
wrote an application using the Java Jakarta POI framework that reads
this spreadsheet and generates other data from it. In general, it
works fine. However, I just discovered a curious anomaly in at least
a single merged region in the spreadsheet.

One merged region is 1 row and 2 columns. There is a single string
visible and centered in the merged region. I discovered that when my
application reads the cells, it finds that visible value when reading
the first cell, but it also finds a value in the second cell, which is
an obsolete value that we used to use.

I can verify this data is present if I select and Copy the entire
second column and paste it into an external editor. The hidden value
becomes visible.

I'm going to investigate whether I can detect this condition with POI,
but I'd like to know if there's some way in the Excel interface I can
detect and fix (remove) these hidden values.