Sandbox refresh feature

[Vijay Khairnar]

How to make sure sandbox refresh feature can be utilized efficiently so that there is no migrated configurations copied over from production to TEST ? 

Also to note I am trying to copy the data to existing sandbox where all production related configurations are already present.

[Robert Nadon]

The process overwrites existing sandbox data and takes up to 30 minutes, commonly used for testing in a realistic environment.  It can copy only certain projects or everything.  As far as "no migrated configurations".  if they are all in a separate projects then you can copy them over.  A big note is that it will NOT copy app data over.