小弟我是新手，请教为何小弟我调用两次pokerdeal（）；时，结果都一样的？求大神相助！

我是新手，请问为何我调用两次pokerdeal（）；时，结果都一样的？求大神相助！！
#include<iostream>
#include<ctime>
#include<iomanip>
using namespace std;
int pokerdeal(int n,int m){
     srand(time(NULL));
     n=rand()%4;
     m=rand()%13;
     {
                 switch(n){
                             case 0:cout<<"方块";break; 
                             case 1:cout<<"梅花";break;
                             case 2:cout<<"红心";break;
                             default:cout<<"黑桃";
                           }
                  m=m+1;
                  if(m>=2&&m<=10) {cout<<m<<endl;}       
                  else {
                       switch(m){ 
                                 case 1:  cout<<"A";break; 
                                 case 11: cout<<"J";break; 
                                 case 12: cout<<"Q";break; 
                                 default: cout<<"K";}
                        cout<<endl;
                        }
        }
        return 0;
}

int firstdeal(int a1,int a2,int a3,int a4){
    pokerdeal(a1,a2);
    pokerdeal(a3,a4);
}
    
int main(){
    double poker[4][13];
    int i,j,s,t;
     
    for(i=0;i<=3;i++)
    poker[i][0]=1;

    for(i=0;i<=3;i++){
                      for(j=1;j>=1&&j<=9;j++)
                      poker[i][j]=j+1;
                      }
    for(i=0;i<=3;i++){
                      for(j=10;j<=12;j++)
                      poker[i][j]=0.5;
                      }
     
     /*for(i=0;i<=3;i++)
     for(j=0;j<=12;j++)
     cout<<poker[i][j]<<setw(4);*/
     //pokerdeal(i,j);
     firstdeal(i,j,s,t);
     system("pause");
     }
[解决办法]
srand(time(NULL)); 去掉
[解决办法]
srand(time(NULL)); 这句放到main里面就好
[解决办法]
time(NULL) 返回的是一个秒数，两次调用的时间差距如果小于1秒，此函数返回的是同样的数值 
srand以它为种子，相同的种子会导致后面的rand方法得到相同的结果