Hope you understand that a multi-value or attachment field involves a hidden table where the data/objects are actually stored.
An attachment field does allow multiple elements and is therefore a type of multi-value field but it is different because it is saving objects, not just alpha-numeric data.
Attachment field has properties: FileData, FileName, FileType
Regular multi-value field has property: Value
I tried various SQL structures for each type of field in attempt to create new records in table B. Nothing works.
It would be easier to just copy the table.
Maybe your example is too simplified. Why would you want identical tables?