Description of problem: pdksh conflicts with ksh. Please port the pdksh package to use the alternatives system so that both ksh and pdksh may be installed at the same time. Reason: oracle requires pdksh or their installer gets cranky, but ksh is often prefered.
You can't install both at the same time, alternatives is overkill for this. If Oracle needs pdksh they should install pdksh. If someone prefers the real ksh, he/she installs ksh. What's the point in having both installed when you can use only one ?