This is simple enough to explain, simply look at the following and see if you notice anything fishy:
toor@toor:~/Desktop/test$ hexdump test
0000000 6464 740a 0a74
toor@toor:~/Desktop/test$ hexdump -C test
00000000 64 64 0a 74 74 0a |dd.tt.|
It's a simple text file, two "d" characters, a newline, and two "t" characters, and another line break. Why the heck would the first invocation of hexdump appear to place things like "ddt(newline)(newline)t"?