Laravel : Duplicate Array Entry in Session

I was trying add list of products into session. For that i used array. But i don't want to store same product again into the session. I used the following controller to avoid duplicate entry in session. But it doesn't work. Means it doesn't let me add to the session array at all. How can i solve the problem? Thanks!

public function postEnquote(Request $request)
    {
        $product = Product::where('id',$request->Input(['product_id']))->first();

        if(Session::has('product')){
        foreach (Session::get('product') as $key => $value) {
          if($value->id === $remove->id){
            return redirect('shop-list');
          }

          else{
              session()->push('product', $product);
          }

        }
      }

    }

via Chebli Mohamed