I have been doing genealogy for many years, and here's what I found out.
Merging can cause you more problems than it's worth. I've done some spectacular messups by merging, and it's hard to fix. You are better off to look at each one, think and make sure that it's a duplicate, and do it the way it's been suggested to you. In my tree, people liked to name their children the same names, over and over, and on some of my people, I have 3 people with the same name born around the same time.
You will catch a lot of errors and you will find yourself saying, "What was I thinking, that can't possibly be right, that doesn't make sense".