All this is governed by the settings in Tools>Options>Tags>Mpeg.
If you want to see what is stored in the V1 tags, tick only V1 for read.
If you want to see what is stored in the tag version with the highest priority, tick V1 and V2 for read.
You will then see the contents of V1 tags for files that only have V1 tags but will always see the contents of the V2 tags regardless whether the file has only V2 tags or V2 and V1 tags.
There is no need to copy one tag version into another as long as they are not out of sync. If they are out of sync, then it becomes tricky.
Depending on the settings for writing, the next saving of tags will write the current display to what you have set.
So if you have set to write V1 tags only, only the V1 tags will be written.
If you have set V2 tags only, you will get only updated V2 tags - if you read V1 only and write V2 only, you copy V1 to V2.
It is best to write V1 and V2 so that they stay in sync.
There is no programmable way to include any conditions. You would have to set which tags you want to read, write and delete. There is no way to see the contents of different tag versions next to each other, you only see the contents of the tag version with the highest priority - V2 is superior to V1.
Set Tools>Options>Tags>MPeg to read and delete V1 tags.
Load the files,
Select the files,
Right-click on the files list and select "Cut tags". This will cut only V1 tags from the files and leave V2 tags as they are.
Remember to reset Tools>Options>Tags>MPeg to the preferred settings.