Hello,

Just tested with OOo 3.3.0(buid 9478) and the issue seems to be exist.

Here's how to reproduce:

1. 	Open Impress with a new or existing presentation.
2.	From the Insert menu, select Table.
3.	Add any number of rows and columns  to the table.
4.      Select any cell and  chose border option beside color, in this select
the option with six lines highlighted(for example) and then select the line
color of the border with any color and now select line style and chose a big
thickness(5pt for example) for more clarity.
5.  Chose  that cell and now right click on it   and go to cell and  chose split
option and split them horizontally or vertically.	

Effect observed: Sometimes the border is shared between the two cells.Sometimes
it is not. Inconsistency of Border sharing when I do splitting of cells.  

System Configuration 

Windows Vista, 4GB Ram , Intel Processor 2.40Ghz

Open Office 3.3.0(DEV300_m70,build 9478)