This happens quite often.

• Delete some linked text.
• Replace it with other linked text.
• Save the page.
• The linked text reappears, and is conjoined to the new text.

Note: Knowing that this happens often, I go to great pains to check that the link really has gone, before adding the new text. I move my cursor, and check that the link properties dialog does not pop up. Still, on occasions like this one, the linked text reappeared anyway.