If you have klinefelter syndrome, can your blood tests have normal testosterone levels?

Yes: Check out http://www.mayoclinic.org/diseases-conditions/klinefelter-syndrome/basics/definition/con-20033637. Not everyone w/Klinefelter syndrome (extra X chromosome) develops all signs & symptoms. However, given that Klinefelter syndrome typically affects testicular development, it's unlikely for someone to have high normal T levels. So while T may be normal, most likely, it's low normal.