Strange blackjack rule at Bet365 and how to deal with it

[spino1i]

One of the blackjack rules which I dont think ive seen in any other casino is:

"If the player doubles and the dealer's first card is of value 11 (ACE), and the dealer gets Blackjack, the player loses both his bets. If the dealer’s first card is of value 10, and the dealer gets Blackjack, the player gets the Double bet back."

How does this effect strategy when doubling down with an 11 against an Ace? How much does the help the house's edge? I looked through wizardofodds.com but couldnt find any mention of this rule..