Steps to reproduce:

1. Log in to back office.
2. Go to Content / Content Types / Content.
3. Start creating new content.
4. Fill in value for input Identifier.
5. Scroll page down to 'Field types' and 'Field definition' sections.
6. Add fields 'Author' and 'Content query' to content section by drag and drop.
7. Replace 'Content query' field place to first position.
8. Verify web browser output.

Actual result:

See attached screenshot.

An exception occurred when user replace position of field 'Content query' in content field definition section.

ibexa-admin-ui-layout-js.js:31007 Uncaught Error: Instance for this DOM element already exists!
    at Object.setInstance (ibexa-admin-ui-layout-js.js:31007:13)
    at new Dropdown (ibexa-admin-ui-layout-js.js:29522:37)
    at ibexa-admin-ui-content-type-edit-js.js:188:22
    at NodeList.forEach (<anonymous>)
    at insertFieldDefinitionNode (ibexa-admin-ui-content-type-edit-js.js:187:15)
    at reorderFields (ibexa-admin-ui-content-type-edit-js.js:276:5)
    at FieldDefinitionDraggable.onDrop (ibexa-admin-ui-content-type-edit-js.js:421:11)

Expected result:

No exception occurs.