Sometimes the request to create a full-width page through the API returns a 400

Issue Summary

When creating pages through the REST API, setting the full-width property will sometimes cause a 400 status response, even though the page gets created.

Steps to Reproduce

1. Try to create multiple pages through the API, including the property to set the page as full-width:

   "metadata": {
           "properties": {
               "editor": {
                   "value": "v2"
               },
               "content-appearance-draft": {
                   "value": "full-width"
               },
               "content-appearance-published": {
                   "value": "full-width"
               }
           }
       }

   Reproducible using the following fetch (just remember to change the page's title each time)

   var data = {
       "type": "page",
       "title": "Test full-width through the API 1",
       "space": {
           "key": "TS2"
       },
       "metadata": {
           "properties": {
               "editor": {
                   "value": "v2"
               },
               "content-appearance-draft": {
                   "value": "full-width"
               },
               "content-appearance-published": {
                   "value": "full-width"
               }
           }
       }
   }
   
   fetch("https://INSTANCE_NAME.atlassian.net/wiki/rest/api/content", {
       "headers": {
           "accept": "application/json",
           "content-type": "application/json"
       },
       "body": JSON.stringify(data),
       "method": "POST"
   })

Expected Results

The request should return a 200 every time

Actual Results

Sometimes (around 50% of the time) the request returns a 400 with the following response:

{
    "statusCode": 400,
    "data":
    {
        "authorized": false,
        "valid": true,
        "errors": [],
        "successful": false
    },
    "message": "com.atlassian.confluence.api.service.exceptions.BadRequestException: Error occurred when updating content property content-appearance-draft. Cannot create new content property, see https://docs.atlassian.com/confluence/REST/latest/#content/{id}/property-create for usage. Property : JsonContentProperty{id='null', key='content-appearance-draft', content=ExpandedReference{idProperties={version=EmptyReference{referentClass=class com.atlassian.confluence.api.model.content.Version}, status=current, id=ContentId{id=2466186355}}, of=some(Content{id='ContentId{id=2466186355}', type=page, title='Test full-width through the API without body 1', status=current, space=ExpandedReference{idProperties={key=TS2}, of=some(Space{key='TS2', name='null'})}, history=EmptyReference{referentClass=class com.atlassian.confluence.api.model.content.History}, version=EmptyReference{referentClass=class com.atlassian.confluence.api.model.content.Version}, ancestors=null (CollapsedList), container=EmptyReference{referentClass=interface com.atlassian.confluence.api.model.content.Container}, childTypes={}})}, version=null} , isSuccessful: false, isAuthorized: false, isValid: false, hasErrors: true, Errors: \"jsonproperty.duplicate.key\""
}

Workaround

Even though the 400 is thrown, the page is correctly created and it has the full-width property set, os no workaround is needed.