Created attachment 76365 [details]
example of how copying within shadow unmerges adjacent cells

below is from the about box
OpenOffice.org 3.3.0
OOO330m20 (Build:9567)

Steps to recreate this problem:

1)  open OpenOffice calc

2)  merge cells A1:D1

3)  merge cells E1:H1

4)  merge cells A2:D2

5)  merge cells E2:H2

6)  select all the merged cells (range A1:H2).

7)  format the selected range with the default shadow (bottom right, 5.0pt, Gray)

8)  Select A1, enter the text "test"

9)  select A1 and copy

10)  select A2 and paste

the merged cells of E2:H2 should become unmerged due to the bug.
if you skip the creation of the shadow (steps 6 and 7), this unmerging does not occur.

I have attached a sample document.  The sample also has a non-shadow range so that you can compare how copying within a non-shadow range does not unmerge cells, while within a shadow does.