I spend so much time helping Ancestry novices undo the duplicated spouses and children on their family trees, that I’m dedicating a post to it.

Understanding how it happens
This is not Ancestry‘s fault—apart from the fact, alas, that its transcriptions can be so unreliable, but I’ll not vent here on that disappointing element.

Adding duplicates is an own goal.  It doesn’t happen the first time you find something that links to a person who is already on your tree. It happens if you unwittingly add, as a ‘new person,’ someone who is already on your tree. It arises because the details in the ‘fresh’ information appear in a slightly different format to what is already on your tree, which leads Ancestry to ‘suspect’ that you are adding a new person.  Perhaps the enumerator interpreted the spelling of the name in a way that was inconsistent with a previous version so, to a Mere Computer, you might be adding a ‘newcomer’ to your tree.

Often it is a new person e.g. when  additional children have been born since a previous census, or when suddenly a mother-in-law is visiting on Census Night.

How to avoid this happening (because it’s going to take a heap of time to undo)
After you click to ‘review’ the hint, remember you’re reviewing a suggestion in order to accept, amend or reject it!

When you click to review , you are taken to a page where the ‘new’ information is on the left.  When Ancestry ‘thinks’ this is a different person to the one you have on your tree, there will be nothing on the right-hand side of the screen.  Usually you will tick (check) the Add box to add that person to your tree.  Instead, override your eagerness.

There are two options to the right of the name of the person you are adding:  ‘NEW PERSON’ and ‘Not a new person?’.  Pause before you act.  Helpfully, at the very top of the page,  there is a summary of what you have about the person on your tree and what is ‘unknown’.  Take time to digest this.

If you recognise that someone is not a ‘new person’, you will avoid duplicating a person you already have, and you will be given the option to connect that information to the person you already have on your tree.