Jira issue navigator search fails for a system field when it is duplicated

Issue Summary

Creating a duplicate of a system field in the Jira instance, example: Request Type (System field) and Request type (Custom Field) creates problem in Issue Search.

Expected Results

Search should work as expected and provide required results

Steps to Reproduce

1. Have a "Request Type" system field and a "request type" custom field
2. Start typing the word "request " into the JQL search and auto-suggest will suggest both fields.
3. Notice that the suggestion for the System Field is "Request Type - cf[00000]"
4. However when you select the suggestion, only the text "Request Type" is placed into the JQL
5. This now makes it ambiguous with the "request type" (lower case) custom field and you will get the error

Actual Results

The below error is thrown in the search results :

There are multiple custom fields with the name 'Request Type'. Try using one of the following terms: cf[10010], "Request type[Checkboxes]", "Request type[Dropdown]". 

Workaround

Search it using "cf[custom field number]" instead.