Windows Media Player burns songs twice

I am having trouble using regular cd-r's. The first time I used the Windows Media Player to make a CD everything went great. I loaded the CD, dragged the four files containing 25 songs in each and made a great data cd with 100 oldies. When I tried to do it again a few days later to make a copy for a friend, the files were burned in the following order.....1,2,3,4,1,2,4,3 and I had 200 songs on the CD, 100 songs TWICE! Thinking this was a fluke, I tried it again using a different file. I used 279 different oldies totalling 660 mb's. When I burned it, all songs came up twice again. First of all, why is it burning twice and secondly, how does 660 mb's burn twice on a 700 mb cd-r???
Thanks, Bobbyob