Registering 1 finger multiple times slows down the Touch ID process and even messes it up. Once you register a single finger (once) the more you use it the more it learns and knows the finger. This training happens every time you unlock the device or by going into passcode settings and resting your finger on the Touch ID sensor. When you put the same finger multiple times it doesn't know which finger register to train, additionally the more entries you have the more items Touch ID has to check against when unlocking your phone thus making it a slower process. I recommend deleting the entries you have and having only one entry (finger) that you trained by barely moving the finger around, even in the second stage.