I can't remove the second one because there is no edit icon for her.
This problem arises because Anna Jorgine Engelsdtr has been shown twice: once with both parents and once with only her mother. If you unlink Anna from her mother in the bottom instance, using the pencil icon on the right, all will be well.
Thank you so much! I didn't expand the listing to see the additional children there.
I find I need to do this all the time. The only need you might have to leave Anna under her mother alone is if she did not have a biological relationship to her mother's spouse. But you could leave her under parents, too, showing her relationship to her mother's spouse was, say, "Step" or "Adoptive".
I would agree with Norm's advice for most cases, however. When detaching a child unnecessarily attached to one parent (it could be mother or father), I add a reason statement such as: "Already correctly positioned under both her parents".
Please excuse me for answering more than the actual question here, but this problem with terminology comes up with a surprising frequency here.
To state the important conclusion here first: You will never have two different people with the same ID in Family Tree.
In the record you discuss, you do not have "two wives with the same ID" and you never will. You are on the one and only the detail page for Sissela M6TK-4YV. The Family Members section of her detail page will show all her relationships and to correctly show those relationships, she will be shown multiple times:
For a person who had four marriages and was adopted, you would see him six times in the Family Members section, all with the same ID, because it is just him being shown in the different relationships.
The reason there was no edit icon in her second relationship box was because she had no spouse there and therefor nothing to edit. That second box, as you were shown, was for the relationship with her child that was duplicated.