Found this photo online. Looks like the second knob was a way to choke up on the bat while still being able to put your wrist on the knob. The author stated that Wright and Ditson manufactured the bat for Nap Lajoie. Turns out a company called Phoenix bats still makes them. I'm not sure how to help on dating the bat, but since the style never really caught on, it makes me think someone made it at home close to when Lajoie was playing. 1920 or early maybe? Just a guess though.
Here's the link to the blog article where I got the info:
http://www.blinddogpix.com/bat/baseball.htm