Can't import Certificates correctly

I have 2 cas servers and 2 mailbox servers.

I created a certificate on CAS01, with my CA server.  (cert request and completed, etc.)

I then exported that cert and am trying to import it on my other 3 exchange servers.

However when I do I get the error,

"A special Rpc error occurs on server CAS02: Cannot import certificate.  A certificate with the thumbprint xxxxxxx already exists."

xxxxx= the whole cert thumbprint.

if anyone knows what is causing this or how to fix, would be greatly appreciated.