How can I have the same ssh key for dual boot (ssh-keygen)

[Kevin Wilson]

I use:
ssh-keygen -t rsa
to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
other machines in order to permit ssh to these machines without being
asked for a password.

The thing is that I have dual boot on this machine: one for fedora and
one for ubuntu. The two key files which were generated on these machine
are different.

Is there a way so that I will have the same key file for both these fedora
and
ubuntu ?

regards,
Kevin