I would assume a true redundant system would have a different input (different input card or rack). Landing to the same input seems more problematic than anything else.
I would agree, we basically have a device with a single 4-20mA output. Due to size restrictions we cannot put a second signal conditioner in to get a second true 4-20mA output.
I could potentially feed the same 4-20 input into separate PLC cards and use separate cabling, but it would always be a replication of the single 4-20mA input.