I was wondering the same thing when my name was printed on my Teacher Recommendations. However, this counts as an "electronic" signature according to the Common Application and is perfectly valid. There is no need to sign it again. Just fill in the box for yes or no for waiving and put the date.
The following is directly from the Common App Website. While it is referring to the general signature of the application, I am sure it also applies to recommendations. I can't get a direct link to the page so just go to the Common App Support Center
and search signature. It's the first response.
"I need to sign my application/supplement online.
Immediately before you submit your online application, you will be asked for an electronic signature. The electronic signature consists simply of your name, typed by you on your keyboard, just as if you were typing it into any other form on a web page. At this time, our system will not accept a graphical representation of your signature.
The signature is your confirmation that the application/supplement you have filled out is your own work and the information is factually true. Once you type in your name and the date, this will count as your "electronic" signature."
Also, just think about it. If colleges would only accept a hand written signature and not an "electronic" signature, then why would the Common Application automatically print your name on the line?