I have one copy of the card Anticipate from the set ikoria lair of behemoths. I have two copies from Core Set 2019. When ever I add one it overwrites the other. How do I fix this issue?

How are you adding the other printing? Is this in the inventory, via the Add Card widget? You should be able to click on "Add New Row" and select the other printing for the new row, then when you click save both of them are there.