T-Rex 0.25.6 now has two different dual-mining modes: one that works in conjunction with the LHR unlock function, and one that is intended for use with non-LHR cards. Unfortunately, these two modes use two different sets of mutually-exclusive options, and there’s currently no (easy) way to work around this problem within HiveOS.
/hive/miners/t-rex/h-config.sh requires a patch to be able to emit either the lhr-algo and lhr-tune options or the dual-algo and dual-algo-mode options in order for HiveOS users to take advantage of this new feature.