first, linky link:
Now specific answers:
@sutechan, no need to keep duplicate COSTUME PATTERNS. They can be used to level up costumes for an insane exp boost.
@Crant, unless you did thousands of pulls, your sample size is not large enough to be representative of the odds.
@Cheds, you could already use duplicate costumes to level up your other costumes. Not a new change 
@Hauset, the chamber shows that there are no New costumes… You can cycle they them all… Also what gave you the impression that there were new costumes? Nothing from beta, nothing on the forum, nothing in game… Idk mate, think you’re on your own here.