Group By - What is best way to Concatenate strings separated by , - but UNIQUE vals?

All -

I use Group By and have many aggregate fields that contain "duplicate" values. Since I have multiple columns that will aggregrate arrays, I can not simply sort and do a unique steps.

Example:

hostname,column1, column2,column3
host123,"a,b,b,c,d,d,","e,e,f,f,g","x,y,y,z"
...

I would like to have the following:

hostname,column1, column2,column3
host123,"a,b,c,d,","e,f,g","x,y,z"

Thanks in advance for suggestions!

KP