Method for handling duplicate index headings

[demery]

See the management guide on duplicate index headings:

An ongoing issue in the index is repeated entries. Some entries occur twice in the index, either in error or by design. For example, "first day" is listed under both "D" and "F." For these entries, there is no good way to distinguish between the two items. For the corresponding numerical entry, we have no way to link to both index items. The code will pick the first item and ignore the second one. There is currently no protocol to correct this, and a future project manager will have to find a solution.

This should be handled in code -- there should be a method for recognizing that there to two headings and showing them both in the wax site.