Reasons to use two:
(a) perhaps one up front and the other in the rear of the living space
(b) one was there, and there's enough free space to add another
(c) they look cuter as a pair?
Yes, you can do as you proposed.
As KCshoots advised, just don't overload the from-the-battery run of #6 wire by the total load. In theory, #6 wire is "good for" 120 amps. It has 0.0004 ohms per foot, so you'd be losing 0.048 volts per foot of wire (at that load).
So five feet between the boxes would involve adding 10 feet of wire, which would knock 0.5 volts out of the game (at 120 amps). It would also "raise" the ground potential of the distant fuse box (the 0.5 volts would be split as "the 12v will drop 0.25 volts, and the "ground" will "rise" 0.25 volts relative to the closer-to-battery box.
That disparity in "ground potentials" can upset things that span the two boxes (say a radio in one box, and a secondary amplifier in the other). If it was AC (instead of DC), you'd pick up a noticeable hummm.
ah.. because they look cuter as a pair, the one I have a 12 way and i have more lines about 16- so wanted to be "comfortable"- You guys not running with this issue? i must do something wring with my wiring. I'll try to combine things and maybe I'll need only one- good to know that I can though- thanks
I have three in my van, as shown in the diagram. I talked to Blue Sea first (who makes the quality marine fused distribution blocks) and they confirmed series is okay, but not to exceed 100 amps total as that is the highest rating for those particular blocks.
I have one in the passenger rear corner inside the electrical box, one on the driver's side behind the galley and one in the overhead compartment. Wiring it this way saves significant amount of wire as you no longer have to return to "home" from each source.