connecting aftermarket deck/confused

[98civex]

ok i have an installation harness that plugs into my car's originally radio harness and the new deck's harness.

they both have ground wires to be spiced together so why do the instructions say to connect ground of radio to bare metal? does it matter?

 

[biggame]

it dosnt matter, splice all the wires together from the radio harness to the aftermarket harness u purchased but cap off the organce wires... n ull b good to go..

 

[Inertial]

Just splice every wire accordingly to the harness and stock wires. Honda did the ground for you already.