yes, schools see all the dats that you have taken. the most recent scores are listed first.
i am also second time applicant. however, i heard that it really doesn't make much of a difference...so it isn't "really good" as you mentioned. in fact, if you are a second time applicant, they look for major improvements. if you havent changed much, they think you haven't tried hard enough. i think we all know how difficult it is to increase your gpa/dat, so it sucks trying to make any major improvement.
basically, second time applicants should be aware that their applications are going to be looked at with more detail (in a negative way) than first time applicants.
good luck.