Multiple public/private key pairs for the same user

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http://serverfault.com – First, sorry if this question has already been asked/answered - I've searched but perhaps I haven't recognised the answer.... What we have is a cluster of servers which need to access a single remote server using sftp. We are migrating from one remote server to another at the same (remote) location. We also want to refresh the public/private key pairs on the configuration as part of an ongoing security review. My question is - can we have multiple public/private key pairs for the same user between server A and server B? I want to do this to allow for cutover testing - but am concerned tha (HowTos)