Britney Spears’ has dropped down and given a double dose of 500k. According to the “Womanizer” singer’s label, “Circus” has sold well over 500k in its first week matching record tour ticket sales. While official sales numbers are slated to hit the net later today, Spears ‘comeback’ album is said to have moved 504, 507 copies topping some of this year’s top releases including recently released efforts from Beyonce and Kanye West. In related news, the “Circus” singer has sold 500,000 tickets for her upcoming “Circus” international tour already ! Tickets for Spears’ tour went on sale Saturday and have been flying off the shelves, so to speak, since the dates were announced. As a result six additional dates have been added in Los Angeles, New Jersey, Chicago, Long Island NY, Toronto, and Anaheim, CA. As previously revealed on Singersroom, Spears’ has tapped the Pussycat Dolls for the North American leg of her highly anticpated tour aptly named after her new album. Click Here for tour dates.