Hi Leon,
As far as standard SAP is concerned, it is not possible to save the condition records in two tables at the same time.
It has to be populated manually and running some ABAP code on regular basis (in background without manual intervention) to copy the data.
In configuration ( SPRO->Logistic General -> Retail Pricing -> Sales Price Calculation -> Control Data for Pricing Table and Data Backup )also at a time, system allows only 1 assignment.
ABAP program approach will be suitable option for you.
Regards,
Amit