Hello! Just wanted to inform you that if wires are placed on Elevated Rails, it spawns 2 signals, one above and one on the elevated rails.
The one on the ground is removable, the other is not.
Also, the power pole spawns on the lower floor, and shows no connection capability with other power poles.

Thanks for the detailed report — you'd found a real bug. The placer entity wasn't
being cleaned up when the base spawned on a different rail layer, which is why one
of the two signals couldn't be removed.

Fixed in 0.6.0: overhead poles now refuse to place on elevated rails entirely
(the item is refunded with a message), since the overhead network doesn't support
elevated track yet. If you have leftover broken poles from 0.5.1, run
/ret_rewire_all in the console after updating — it cleans up orphaned pole parts
across the whole map. Proper elevated rail support is on the roadmap.