Formulatext column is causing duplicate results

I'm performing a search on all customers. I have a custom field on customer records that holds the id of a chosen contact. I've formatted the search columns like so to get the chosen contact's info:

var contactName = new nlobjSearchColumn('formulatext');
contactName.setFormula("CASE WHEN {contact.internalid} = {custentity_customcontact.ID} THEN {contact.entityid} END");
columns.push(contactName);

For testing I filter the search on my test customer ID. Without the formulatext column, I get one response object. With the formulatext column pushed onto my columns, I get two response objects. One with the entityid of the desired contact. The other response object has the entityid column blank, or a default value. For example when I include "...THEN {contact.entityid} ELSE 'default value' END", a second object is returned with "default value" in the contactName column.