A Basic Concept to remember when building your tree is that:

"Each of your Ancestors was just one person in History".

Therefore they should be entered in your Tree Only Once.

From then on they get linked or connected to others in the tree based on relationships (mother, father, and spouse). When events happen to people already in your tree, and you need to connect to them, always use "Select an Existing Person" instead of adding New. Doing otherwise will result in Duplicate Persons in your data.