This is a mechanic bug I have come across whilst deck brewing a deck for mill in standard. The interaction between the cards Doommaiden and Package Dealer needs to be reviewed.
As it currently stands, the text of Doommaiden is the following;
“Draw a card from your opponent’s deck. If you don’t play it this turn put it back.”
And Package Dealer reads:
“When you draw a card you have a 50% chance to draw another.”
Any reasonable individual that reads this would say, so if I draw from the opponent’s deck whilst package dealer is onboard - I should draw another… 
. Unfortunately, that is not the case, Instead it will have you mill out of your own deck.
This is a simple id check up on package dealer to check the draw source. XX. if not the case - maybe change the labeling on the card so it is more clear. I have no issue with this combo as it is 10 + mana and would require tons of set up. Just wanting to clean up card interactions. worse comes to worse - those cards would go back into deck, please provide some insight as to why this interaction doesn’t play as read.