No Merge will create the second row if you will use index also on datatable so it will treat as a primary key.
so you can get some idea from here:
let me know if still face some issues 
Regards…!!
Aksh
Anil_G
ashokkarale
kouhei_yamaguchi
ppr
Nabin_Timalsina
sharazkm32
banksmegacorp
alexis.mendoza.rpa
m.takamiya
Honda