SED failure

$ rm test*
$ echo -ne '\x8f\x15\x42\x02\x24\xc2' > test
$ sed 's/\x15\x42\x02/\x12\x12\x02/g' test > test1
$ sed 's/\x42\x02\x24/\x12\x12\x02/g' test > test2
$ md5sum test*
d1c66101d794687bf5d61b5ae4b7da03  test
df353ed72c4918825eeb905b4030536e  test1
d1c66101d794687bf5d61b5ae4b7da03  test2