Twins pop up when you run Edit > Find Duplicate People because their birth dates are the same. Sometimes that is a good thing because you actually can have duplicate people that appear to be twins. Unfortunately, and more often than not, twins are easily mistaken as duplicates. We want to keep our twins separate so here is a quick tip. Add the following in the Birth>Description field: “Twin with Sam Jones”. Of course, Sam Jones should be replaced with your twin’s name. Now, when you run ‘Find Duplicate People’ and compare/match you will see the description under the birth field and prevent merging twins into one person.
How To Prevent Merging Twins When Running Find Duplicate People