Dual Ground on Arco Zeus Regulator with Lynx NG system

Hello,
I just received my new Lithium NG ( 2x 300A/12V) the Lynx BMS NG 500 and accessories.
On the other side i purchased an Arco Zeus Regulator for my 12V/115A Volvo penta Alternator.

Something strange rise up.
In the following diagramm Arco Zeus and Lynx BMS Diagram by Victron the two ground wires from Zeus are connected together to the alternator instead of

  • one ground for the alternor for the Field current
  • one ground for the battery voltage measurement ( ?? )

So which correct cabling is the right one (Arco or Victron) ?
In attachement, see the Arco Zeus installation guide.
Kind regards
Christophe
ARCO ZEUS Installation Guide.pdf (2,5 Mo)