I had a look through the forum, but only found very very old stuff about it.

When using RandomImages

It happens very often the same image shows often 2-3 times on refresh. Is there a way to stop that from happening by somehow check what images have been shown and not get copies of the same images?

EDIT:
As well, why it does not get the correct crop of images like it does in the albums, when a special crop has been assigned in admin?

The function chooses randomly and as far as I know there is no check for checking if the chosen image has been chosen before.

The function probably does not use the custom crop values, possible that we forgot to update it. Best you open a ticket.