Should Lich and Clarity stack?

[tristantio]

This seems to have been removed late in 2001 http://www.tski.co.jp/baldio/patch/20010710.html - anyone know if this was a bug introduced sometime after Velious and then removed later, or if Lich + Clarity stacked (or do they stack?) on Classic/Kunark era?

[Mac Dretti]

Negative afair; necro would be a machine gun if they stacked