#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define SZ(x) ((int)x.size())
#define L(i,u) for (register int i=head[u]; i; i=nxt[i])
#define rep(i,a,b) for (register int i=(a); i<=(b); i++)
#define per(i,a,b) for (register int i=(a); i>=(b); i--)
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef pair<int,int> Pii;
typedef vector<int> Vi;
template<class T> inline void read(T &x){
    x=0; char c=getchar(); int f=1;
    while (!isdigit(c)) {if (c=='-') f=-1; c=getchar();}
    while (isdigit(c)) {x=x*10+c-'0'; c=getchar();} x*=f;
}
template<class T> inline void umin(T &x, T y){x=x<y?x:y;}
template<class T> inline void umax(T &x, T y){x=x>y?x:y;}
inline ui R() {
    static ui seed=416;
    return seed^=seed>>5,seed^=seed<<17,seed^=seed>>13;
}
const int N = 233333,mo=1e9+7;
int cntp[N],cntm[N],qzm[N],mi[N];
int n,a[N],cnt[N],fac[N],ifac[N];
int power(int a, int n){
    int res=1;
    while(n){
        if(n&1)res=1LL*res*a%mo;
        a=1LL*a*a%mo;n>>=1;
    }
    return res;
}
void init(int n){
    mi[0]=1;rep(i,1,n)mi[i]=2*mi[i-1]%mo;
    fac[0]=1;rep(i,1,n)fac[i]=1LL*fac[i-1]*i%mo;
    ifac[n]=power(fac[n],mo-2);
    per(i,n-1,0)ifac[i]=1LL*ifac[i+1]*(i+1)%mo;
}
int A(int n, int m){return m>=0&&m<=n?1LL*fac[n]*ifac[n-m]%mo:0;}
int C(int n, int m){return m>=0&&m<=n?1LL*fac[n]*ifac[n-m]%mo*ifac[m]%mo:0;}
int main() {
    int T;read(T);init(N-1);
    while(T--){
        read(n);rep(i,0,2*n)cnt[i]=cntp[i]=cntm[i]=0;
        rep(i,1,n*2)read(a[i]),cnt[a[i]]++;
        int res=1,cur=0;
        rep(i,1,n*2)if(cnt[i]){
            if(cur==1&&cnt[i]%2==1){
                res=1LL*res*C(cnt[i],cnt[i]/2)%mo;
            }
            else if(cur==1&&cnt[i]%2==0){
                res=1LL*res*(C(cnt[i],cnt[i]/2)+C(cnt[i],cnt[i]/2+1))%mo;
            }
            else if(cnt[i]%2==1){
                res=1LL*res*2*C(cnt[i],cnt[i]/2)%mo;
            }
            else res=1LL*res*C(cnt[i],cnt[i]/2)%mo;
            cur+=cnt[i];cur%=2;
        }
        printf("%d\n",res);
    }
    return 0;
}