Characters getting added twice ? And auto-addition logic

I see some characters are being added twice here, how is this possible ? Also, how does the auto-addition logic work ? I don’t want to add more characters than I can handle. I’m only studying writing.

You can set a limit on the amount of characters to add per day. The number you should set really depends on how long you intend to study each day. I’d suggest starting with something low.
Additionally " Add word frequency " controls when new words are added. I think “slow” sets it to add new words when you have finished learning your due items, while fast will also add new words even if your queue is still long. You should