Deduping records without loosing right data

Hi guys, I am going to merge 2 data files downloaded from different CRM systems, some is more outdated than another.
i want to remove duplicates but make sure that deduplication doesn't lead to deleting newer data (date is not attached to records - i just know which database is newer, yet the older one has some records that the new one doesn't have - that's why i need to merge and dedup).
How do i go about it?

Thank you.

Hello,

Someone can confirm or deny this, but I think the remove duplicates function runs from top down, so as long as your new data is physically located higher than the older data it will take precedence.

Best of luck,