title: Add multiple users to SharePoint Online document library item "Person or Group" column using Client Side Object Model (CSOM)
body: <p>I am attempting to add multiple users to a field using CSOM. However, only one person is being added even though both have been validated.</p>
  
  <pre><code>var newUserField = new List&lt;SP.FieldUserValue&gt;();
  newUserField.Add(new FieldUserValue { LookupId = 14 });
  newUserField.Add(new FieldUserValue { LookupId = 11 });
  newListItem["MultiUserField"] = newUserField;
  newListItem.Update();
  ctx.ExecuteQuery();
  </code></pre>
  
  <p>That code always only adds user 14. I have also tried:</p>
  
  <pre><code>newListItem["MultiUserField"] = newUserField.ToArray();
  </code></pre>
  
  <p>Every reference I have seen says this should work, and it's not throwing any errors.</p>
  
  <p>I have also verified the column allows multiple entries, and have added both users manually as a test. Could this be a document library CSOM limitation? Most references I have seen are using a list.</p>