No, only one EtherTalk Card is required to communicate in EtherTalk 1.2 and
EtherTalk 2.0 packets on the same network.
Complete details on this, including installation, are in Chapter 3 of the
"AppleTalk Phase 2 Introduction and Upgrade Guide". This document was included
in the "LAN Minds, Volume 1" binder under tab 9.