Payroll deducting Pre as well as Post Tax in Dental Health Plan

Dear All,

Scenario: Benefits are processed in Payroll USA.

If an employee switches to Pre tax deduction then post tax from before, Payroll Results log should show only 1 Wage Type  ( configured for Pre tax ) . however Payroll is deducting Pre and Post tax. It is reflecting both wage types. What am I missing ?

Thanks

Roma