Page 1 of scarey and how !?????

a friend of mine just had a replacement sim and fone delivere by O2 after a theft, fone wasnt used since theft either.
prblem is, once the sim had been activated, as per O2 directions, it came up with ALL THE ORIGINAL NUMBERS AND NAMES !
now, numbers i could accept since tis possible for them to see the most frequently called numbers and add to sim details, " but certainly not the names too !
friend had never used a system like carfone warehouses sim copying service so there was no way anyone had details of names etc
anyone else seen/had this happen ??
and if they can see details like names n numbers, what else are they able to do ?

I know some phones ask u to save to sim or save to phone. Ive brought phones from ebay and when ive put my sim in it has some of there phone numbers still on it.