As explained thoroughly in this thread https://community.sdl.com/product-groups/translationproductivity/f/90/t/15570 I would like a feature to be added to allow duplicate TUs for source/target pairs that are the exact same. Currently, such feature only exists if the target differs. This feature could be present during alignment imports into TM or within the Update Main Translation Memory batch task. As explained in the thread, keeping the original TUs is essential for maintaining quality and reliability with our translation. All our TUs have robust, detailed fields, therefore "allow multiple values" is impractical. 

Another option could be to "add new translation units if the field values differ"

Or "add new translation unit as write-protected TUs" 

The latter option would prevent important data from being overwritten. I'd like certain documents to always stay associated with a certain project and currently, adding a TU with the same source and target but with different fields from a different project would overwrite the original TU. 

Please consider this addition.