After some testing I would insist that this is a bug:
I renamed the deck that I want to insert from '11.Greedtrap' to 'Cover'.
When I insert this deck (doubleclick in the compositions tab), it still replaces the original '11. Greedtrap' deck!
Apparently the deck still "remembers" that it is a copy (save composition as...) and wants to replace the original deck. Please Resolume, stop that nonsense.