Quantum　feedback　control　(QFBC)　and　quantum　feedforward　control　(QFFC)　are　two　major　techniques　for　protecting　quantum　states　against　decoherence.　Based　on　this,　Guo　et　al.　proposed　a　scheme　by　combining　the　QFFC　and　the　minimum-error　discrimination　(MED)　to　realize　a　better　effect　of　discriminating　two　non-orthogonal　states　after　passing　a　noisy　channel　(Phys　Rev　A　91:022321,　2015)　than　the　scheme　without　the　QFFC.　Recently,　Cao　et　al.　proposed　a　novel　composite　control　scheme　for　protecting　such　states　(Phys　Rev　A　95:032313,　2017),　where　QFBC　and　QFFC　are　combined.　They　showed　that　the　performance　of　the　composite　control　scheme　is　better　than　that　of　the　previous　control　schemes　in　terms　of　the　success　probability　and　the　fidelity.　In　this　paper,　we　examine　the　discrimination　scheme　by　combining　the　composite　control　and　the　MED　and　observe　an　interesting　phenomenon,　i.e.,　better　quantum　control　does　not　imply　better　discrimination　effect.　Finally,　we　explain　this　phenomenon.