the LH500 is 350w at 8 ohm, 500w at 4 ohm. Most solid state amps must be run at 4 ohm to achieve their maximum output, hence you connect two 8 ohm cabs in parallel
With the cabs in 8 ohm mode, either of the two pictures are the right approach.
The only difference is that the load is split in parallel at the first cab in pic 1, instead of splitting it at the amp as in pic 2.
I can see the confusing factor though, as Hartke apparently didn't consider daisy-chaining cabs when they wrote the 8 ohm labels. Maybe labeling would help on the true split signal / bridging LH1000, but on the LH500 it's not really helping