I just tried the following on a Linux system and I think the result is correct:

perl -MEncode=encode -e '$x="a\015\012b"; $ucs2 = encode("UCS-2BE", $x
+); print $ucs2' | hexdump
0000000  \0   a  \0  \r  \0  \n  \0   b                               
+ 
0000008
[download]

Maybe a Windows or ActivePerl problem?