On a lease, is a faxed copy of a signature legally binding, or does the contract need original signatures?

I have a lease, and I am a real estate agent. I got a copy of the lease e mailed to us, from another agent, but the broker wanted an original document fearing copies of signatures are not legal in court. We got checks delivered, but not the original document. The credit was approved, the checks deposited, intention to sign the lease by my broker, but he wanted to wait to sign them until he got the original signed lease. The other agent, was pretty upset that this was required, and stated that copies of signatures are legal. Is this true?