ssh-multiadd adds multiple ssh keys to the ssh authentication agent.
These may use the same passphrase. When run without arguments, it
adds $HOME/.ssh/identity and $HOME/.ssh/id_dsa.  Alternative file
names can be given on the command line or in the configuration
file. It uses ssh-askpass if necessary. Unlike ssh-add, if any of
the keys use the same passphrase, you will only need to enter each
unique passphrase once, and keys that are already added will not
be prompted for again.