Whats non-standard about it? Call it p2p_hash, and check to see if
argv[0] is exactly bt_hash or ed2k_hash, and apply a different default
behaviour. Otherwise nothing changes. Lots of programs do this.
Yes a lot of programs do that, such as gzip. gunzip is sometimes simply
a symbolic link to gzip, when called as "gunzip", gzip -d runs. It
seems on my Debian unstable installation it's a hard link
$ ls -li /bin/{gzip,gunzip}
1233293 -rwxr-xr-x 4 root root 53676 May 23 03:12 /bin/gunzip
1233293 -rwxr-xr-x 4 root root 53676 May 23 03:12 /bin/gzip
It appears that this is standard procedure to me. =)