I have exported the contents of a table with transaction SE16, by selecting all the entries and going selecting Download, unconverted.

I'd like to import these entries into another system (where the same table exists and is active).

Furthermore, when I import, there's a possibility that the specific key already exists for a number of entries (old entries). 

Other entries won't have a field with the same key present in the table where they're to be imported (new entries).

Is there a way to easily update my table in the second system with the file provided from the first system? If needed, I can export the data in the 3 other format types (Spreadsheet, Rich text format and HTML format). It seems to me though like the spreadsheet and rich text formats sometimes corrupt the data, and the html is far too verbose.

**[EDIT]**
As per popular demand, the table i'm trying to export / import is a Z table whose fields are all numeric, character, date or time fields (flat data types).

I'm trying to do it like this because the clients don't have any basis resource to help them transport, and would like to "kinna" automate the process of updating one of the tables in one system.

At the moment it's a business request to do it like this, but I'm open to suggestions (and the clients are open too)