Does joint life insurance payout twice?
Simply put, no. Life insurance pays out once, whether it is a single or joint policy. Most couples need only one joint policy to cover mortgages and protect the surviving partner.
Single vs Joint Life insurance
Most couples only need a joint life policy but single life insurance policies might be better for some couples. If you split up, you would probably want to take out your own policy so some couples stick with single life policies to cover that eventuality. You may have taken out a single life policy before you met your partner and if you were young and fit, it is likely the premiums were low and it may be worthwhile sticking with that.
The best thing to do is to get a quote for single life insurance and another for a joint policy. That will allow you to judge what is the best option for you.