Issue Summary

Custom fields for TMP project's filter subscription show duplicate columns when similar custom fields created with different case formats.

Steps to Reproduce

1. Create a global custom field
2. Create a custom field of the same type and same name, but different case letters (Eg End date and End Date)
3. Go back to the old issue search.  Add the column in old issue navigator.
4. Add the field to the column config. You will see both fields in the available options, doesn't matter which one you select (you can select both as well).
5. Run the subscription.

Expected Results

We should get the subscription email similar to that of the filter results in the UI. In the UI we only see on column for the custom field.

Actual Results

We see duplicate columns.

Workaround

All the custom fields with different case formats be made into one format.

If two formats being used, End date and End Date, we can change both of them to one format like End date and End date.