Duplicate next_steps entries when exporting parallel objects in v1.3

When exporting playbooks from the IOB reference implementation in version 1.3, next_steps actions within parallel objects are being duplicated. An action that was already duplicated on import ends up multiplied again on export. An object imported that has 1 duplicate step or 2 copies becomes 4, then 8, etc. on export. It also seems inconsistent, not affecting every parallel step block but in my case had affected ~half. I manually cleaned a json object, imported and did not have duplicate steps. It's fairly apparent when there are, because the relationship edge lines connecting the blocks in the view appears bold. The duplicate steps always lay on the same exact path as the others.

"parallel--f21e3309-f95b-52ee-a963-d6ed41d3cca8": {
  "type": "parallel",
  "step_extensions": { … },
  "next_steps": [
    "action--58a39aa9-5334-54fc-8842-a304d8f95e08",
    "action--710e1e69-2475-5d66-a385-5e6fc06d657e",
    "action--01df3b29-8200-5c7d-bb6f-d0b703886683",
    "action--01df3b29-8200-5c7d-bb6f-d0b703886683",
    "action--01df3b29-8200-5c7d-bb6f-d0b703886683",
    "action--01df3b29-8200-5c7d-bb6f-d0b703886683"
  ]
}