Unicode conversion and System Copy

Hello

I am going to perform a unicode conversion. The procedure mentioned in SAP service marketplace is to perform system copy, perform unicode pre-conversion steps, perform export with R3load and then import.

My question is if I perform a system copy from prod to sandbox, then perform unicode pre-conversion steps and export PROD with R3load, which will convert it to unicode, then when I do import, doesn't it duplicate the already existing non-unicode sandbox instance which was copied in the first step from PROD.

To summarize my question, I mean should I perform a system copy of non-unicode PROD to sandbox, or should I just created a empty database unicode sandbox instance and then import unicode converted exp files of PROD into this sandbox?

Kindly help me in this matter.