Just had a match where Greg cast a Moritte and chose to exile it and make a copy of my highest cost thing. I had a Svella, Ice Shaper and a Mask of Griselbrand out which both cost 12 mana. When Moritte made a copy it copied both things instead of picking one of them.
Hello @stikxs,
Thank you for all the information provided, this issue will be investigated!
If you have any additional information that you consider relevant, please don’t hesitate to send me 
Rebeca