Yes, this is a recurring bug that has to do with sets with multiple images. Sometimes both images in the set end up with the same position in our database.
We can fix it manually each time, but sometimes some hours go by before we can fix it, due to devs being asleep or busy with other tasks.
Ultimately the underlying bug hasn't been fixed yet. We would love to know how to reproduce this one so we can fix it.
Thanks for your reports.