Remove superfluous filters

app/controllers/cost_reports_controller.rb

@@ -169,6 +169,10 @@ class CostReportsController < ApplicationController
   #   sets the @cost_type -> this is used to select the proper units for display
   def set_cost_type
     if @query
+      existing_filter = @query.filters.detect { |f| f.is_a?(CostQuery::Filter::CostTypeId) }
+      if existing_filter
+        @query.remove_filter(existing_filter)
+      end
       @query.filter :cost_type_id, operator: '=', value: @unit_id.to_s, display: false
       @cost_type = CostType.find(@unit_id) if @unit_id > 0
     end