function error

here is the line of code with the error: function minusmana () {

the error im getting says: Type "Player" already has a definition for "minusmana".

does anyone know what it means?

here is the whole script:

 var lefthand : Transform;
 var righthand : Transform;
 var spell : GameObject;
 var spell1 : GameObject;
 var spell2 : GameObject;
 var spell3 : GameObject;
 var spell4 : GameObject;
 var spell5 : GameObject;
 var spell6 : GameObject;
 var spell7 : GameObject;
 var spell8 : GameObject;
 var spell9 : GameObject;
 var spell10 : GameObject;
 var spell4u = 0;
 var spell5u = 0;
 var spell6u = 0;
 var spell7u = 0;
 var spell8u = 0;
 var spell9u = 0;
 var spell10u = 0;
 var health = 100;
 var mana = 100;
 var maxHealth = 100;
 var dummy = 0;
 var minusmana = 0;
 
 
 function Start () {
 spell = spell1;
 Invoke("recharge",0.1);
 minusmana = 10;
 }
 
 function recharge () {
 mana += 0.5;
 health += 0.1;
 Invoke("recharge",0.1);
 }
 
 function minusmana () {
 mana -= minusmana;
 }
 
 function Update () {
 
 if (mana >= maxHealth){
 mana =  maxHealth;
 }
 
 if (health >= maxHealth){
 health =  maxHealth;
 }
 
 if(Input.GetButtonDown("Fire1")){
 if(mana >= minusmana){
 Instantiate(spell, lefthand.position, lefthand.rotation);
 Invoke("minusmana",0);
 }
 }
 
 if(Input.GetButtonDown("Fire2")){
 if(mana >= minusmana){
 Instantiate(spell, righthand.position, righthand.rotation);
 Invoke("minusmana",0);
 }
 }
 
 if(Input.GetKeyDown("1")){
 spell = spell1;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("2")){
 spell = spell2;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("3")){
 spell = spell3;
 minusmana = 40;
 }
 
 if(Input.GetKeyDown("4")){
 if(spell4u == 1);
 spell = spell4;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("5")){
 if(spell5u == 1);
 spell = spell5;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("6")){
 if(spell6u == 1);
 spell = spell6;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("7")){
 if(spell7u == 1);
 spell = spell7;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("8")){
 if(spell8u == 1);
 spell = spell8;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("9")){
 if(spell9u == 1);
 spell = spell9;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("0")){
 if(spell10u == 1);
 spell = spell10;
 minusmana = 10;
 }
 }
 
 function OnGUI () {
 GUI.color = Color.red;
   GUI.HorizontalScrollbar (Rect (Screen.width * 0.1, Screen.height * 0.87, 180, 15), dummy, health, 0, maxHealth);
   GUI.color = Color.blue;
   GUI.HorizontalScrollbar (Rect (Screen.width * 0.1, Screen.height * 0.9, 180, 15), dummy, mana, 0, maxHealth);
 }