Hi,
In Geneanet (declinaison of Geneweb), I use a very useful function to avoid creating a duplicate individuals. Let’s show you 
I have lots of Nikolaus RUPP in my tree. If I create a new one, Geneanet show me a list of personbn who have almost the same first name or almost the same last name.
I can navigate in this list and try to find a similar personn. I can have some details.
And I find the same personn, I can just select him (“Relier cet individus”) and I don’t create a duplicate one.
It might be interesting to have a similar function to avoid creating a duplicate.