While working through the articles marked by the bot I noticed that the bot sometimes doubles the links instead of replacing the original.
Examples:

Here a link was mistakenly marked as dead and duplicated:
https://de.wikipedia.org/w/index.php?title=Fahrraddiebstahl&diff=211644488&oldid=211589793
And here the link was already marked as an archive link and the bot added it again:
https://de.wikipedia.org/w/index.php?title=Nahverkehr_in_Saarbr%C3%BCcken&diff=211793149&oldid=211768186