Duplicate I/O Modules

This is on a ControlLogix system with 1756 I/O and redundant controllers using 1756-CN2R modules.

Can anyone tell me if it makes sense to increase PLC system reliability with duplicate I/O modules by wiring discrete inputs and outputs to two different input or output modules?
Input example: one fused 120VAC limit switch wired to two different 1756-IA16 in different racks. If the inputs were different (one input on and one input off) for a period of xx milliseconds then one of them is wrong. It would not be known which was wrong. I guess the program could register a fault for that point and stop the machine.
Output example: two 120VAC PLC outputs each with their own fuse in different I/O racks wired in parallel to a common terminal block to one solenoid valve in the field. The PLC logic will turn both outputs on and off together. If an output fails OFF then the second output still controls but no-one will know that one has failed until the second output fails. If an output fails ON then the second output can do nothing and system is no better than a normal single output arrangement.
Maybe this doubling of I/O modules will double the probability of faulty modules and the system will be no further ahead.
Any comments appreciated.
Thanks.

I really see no use for that idea. Redundancy has it's places, but unless you have an absolutely critical need, this isn't one of them.

Besides, if you absolutely must have this level of redundancy, then you probably want separate racks entirely, wired up to yet another supervisory voting system. Yech.