Adding clefs mid-line (when both clefs are treble, for example)

Is there a way to add a clef mid-bar, if it's not a change of clef but the same one? I'm writing recitative and need to insert a new clef each time the character singing changes. It works fine if they are in different clefs, but if both characters use the treble clef I can't seem to get an extra treble clef into the line. Does anyone know how this might work? Thanks!