I've got four BL-5Js purchased at different times at different locations. Two of them are "Made in China" the other two "Cell made in Korea Further processed in China". All of them look like the battery on your pic's right, i.e. have the "ear flaps" on the top near the connector, so I'd think if the actual capacity is the same as the one on the left then it's probably original.

Three of my batteries came with the original Nokia handsets (5800XMs & N900), one I bought separately. I swap them quite often among each other so I know all of them have about the same "life" in them, i.e. about two days in my N900 when I use it intermittently.