Adding to Peter's comments,
I was wondering if you are join condition is correct and still you are getting multiple records ( incase you are doing a cross join? )
Apart from that as peter suggested you can try both the options to eliminate the duplicate records.
Suggested approach is through "GROUP BY" but you can check with "DISTINCT" ( wonder since HANA is columnar will distinct work better than GROUP BY? )
You can check the performance through Viz plans and let us know
Regards,
Krishna Tangudu