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If a narrow, trusted channel is needed (for example, there is an usb key to take data between the machines), it is okay.
Although SSH will throw a big error if it tries to connect to a server pretending to be another one (RSA fingerprint wont match), it can't happen if the servers don't know eachother (also they don't know eachothers key as well). In this case - also before the first connection - a MitM attack is possible, AFAIK.
The best were a command sequence on both side, which generates the needed keys on both sides.