Copy Random Bytes to Clipboard on OS X

I'm working on a challenge on Over The Wire, and I can't even get past the first one because I can't copy arbitrary bytes to the OS X clipboard. I'm trying to use this command to copy the data to my clipboard:

echo -ne "AAAAAAAAAAAAAAAAAAAAxefxbexadxde" | pbcopy

Then, I ran pbpaste | xxd to check if it copied correctly:

I expected to get this output:

00000000: 4141 4141 4141 4141 4141 4141 4141 4141  AAAAAAAAAAAAAAAA
00000010: 4141 4141 efbe adde                      AAAA....

But instead, this is what was copied:

00000000: 4141 4141 4141 4141 4141 4141 4141 4141  AAAAAAAAAAAAAAAA
00000010: 4141 4141 c394 c3a6 e289 a0ef ac81       AAAA..........

I tried using echo -ne "AAAAAAAAAAAAAAAAAAAAxefxbexadxde" | LANG=C pbcopy, LANG=C pbpaste | xxd, and pbpaste -Prefer txt | xxd, but non of those worked either. How can I get OS X to not mess with what I'm copying?

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