When real property or an interest therein is purchased or condemned for highway purposes and a fence or building is located on such property, the governmental agency shall be responsible for all costs incurred by the property owner in replacing or moving the fence or moving the building onto property owned by the landowner and abutting the property purchased or condemned for highway purposes, or the governmental agency may replace or move the fence or move the building. Such costs shall not constitute an additional element of damages which would permit unjust enrichment or a duplication of payments to any condemnee.