LSD-Studio
HCAF crusher
If that is the case they are probably trying to use an EQ matching program like HarBal or Firium to match the EQ curve of the finished song to yours. You should never master a song to make it sound like a different song. You should master a song to bring out the best in that song. Furthermore, mastering is more about bringing multiple songs together to make a cohesive product and less about trying to make songs sound "better." The mix should bring you about 90% to finished...mastering is the last little bit to polish everything off.
+1