This shows the Lofrans Progress I primary windlass installation with rope gypsy option. note that the starboard cleat was moved starboard 2" to clear the chain. A second windlass (not shown) has been installed (same type but without the rope gypsy) to port and just forward of the primary windlass. The port cleat was moved to the centerline to clear the chain.
A second roller was added by adding a secondary SS platform that bolts on to the original platform. When using two anchors, both lines are led over the primary roller so the bolt-on platform carries no load. The secondary platform and roller is only used to set and lift the secondary anchor and to provide a storage location for it.
Both windlasses are powered from the same breaker added just above the breaker panel (no pic available). There are deck-mounted sealed switches port and starboard for the associated windlass. The breaker is sized for using only one windlass at a time but there is never any reason to use two at once anyway.
To set two anchors, I normally set the primary anchor upstream or upwind (depending on circumstances) and let out almost double the intended scope. Then I lower the secondary anchor and feed out the rode as I bring in the primary rode.