#include <bits/stdc++.h>
using namespace std;
int a[100010], ans[100010];
int main() {
  int t, n;
  cin >> t;
  while (t--) {
    memset(ans, 0, sizeof(ans));
    cin >> n;
    for (int i = 1; i <= n; i++) {
      cin >> a[i];
    }
    bool ok = 1;
    map<int, bool> mark;
    for (int i = 1; i <= n; i++) {
      if (i > a[i]) {
        ok = 0;
        break;
      }
      if (!mark[a[i]]) {
        mark[a[i]] = 1;
        ans[i] = a[i];
      }
    }
    queue<int> q;
    for (int i = 1; i <= n; i++) {
      if (!mark[i]) {
        q.push(i);
      }
    }
    for (int i = 1; i <= n; i++) {
      if (!ans[i]) {
        ans[i] = q.front();
        q.pop();
      }
    }
    if (!ok)
      cout << -1 << endl;
    else {
      for (int i = 1; i <= n; i++) cout << ans[i] << " ";
      cout << endl;
    }
  }
}
