I installed gentoo x86 on my amd64 computer. When I emerge beecrypt-4.1.2-r1, the emerge will automatically add --with-arch=athlon64 to the configure script. However, configure will define OPTIMIZE_I386 instead of OPTIMIZE_I686 for CFLAGS for athlon* arch. This will result in not defining ASM_AESENCRYPT and so on, which will cause multiple definition of aesEncrypt: one in aes.c and one in masm/aesopt.i586.asm.
*** This bug has been marked as a duplicate of 124900 ***