Hi IFF,
Really it is good to copy one plan version to another plan version because just assume that you are company has two branches one is in US another one is India.
Create one for India plan version : IN
Create one for US plan version : US
Now copy IN & US into Current plan version 01.
Now take it one exp :
if one of you are core user will delete some data in India how will you find which data is lost in this situations directly you can copy 01 Plan version all data to IN plan version.
To copy plan version : RE_RHCOPL00
For more clarification click on below link
SAP plan version Transaction Codes
I think you are cleared now if you feel this useful information kindly close this ticket by clicking correct answer.