The AMQ-7 mainline documentation contains this critical warning about configuring replicated HA:

Replication requires at least three live-backup pairs to lessen (but not eliminate) the risk of network isolation. Using at least three live-backup broker pairs enables your cluster to use quorum voting to avoid having two live brokers.

This warning is missing from the JBoss EAP 7.0-7.3 documentation and the documentation presents examples of replicated / replicated-colocated messaging consisting of 2 live/backup pairs.

Configuring replication with fewer than 3 live / 3 backup nodes dramatically increases the risk of a split brain scenario (with potential for corruption / message loss), as replication relies on quorum voting to make a go-live determination when a master appears to be unavailable. Since quorum-size effectively equals cluster size with fewer than 3 nodes, quorum voting is ineffective with fewer than 3 lives (no majority available in the absence of a single live node).