It is in fact the same plant. What you see is called it's juvenile stage. Common for the juvenile leaves not to resemble the mature leaves in a lot of species. It will produce from it's new pups the common leaves of the main plant after it matures. This proves that all Sansevieria came from the same stock at one time. Or so the theory goes.

Maybe your longer leaves are from lower light?

Stick with it, whatever it is. The pup looks like a juvenile, as Stush wisely says. It may look different as a mature plant -- but judging from how it looks now, it will be very attractive. Stick with it and nurture it. I think you will be very pleased with it when it grows another season or two.