This post will reflect my own personal opinions and the way that I dive.
I believe that it is better to use two identical computers for the simple fact that it is much easier to remember how to operate (as in gas changes, etc.) than to remember 2 different computers. I know that there is also a slight chance that either a hardware or software issue in one unit may also be an issue in the second unit too. I dive with 2 Shearwater Predators and have full trust and faith in them. I may on occasion run a slightly more aggressive gradiant factor in the second unit for a " if the brown stuff hits the oscillating blades" moment in order to get out of the water a bit faster.
I dive a rebreather and the redundancy is very important if for no more reason than to cross check between the two and verify that things are right.
Most of my dives require decompression and redundancy is important there too. I prefer a second computer over tables and a timer.
There is no right or wrong answer to the OP question. It is a matter of knowing the risks of either option and making an informed decision that you are comfortable with. I know what Is comfortable for myself and using 2 of the same works very well for me.
There is no need for different algorithyms either. How will you be able to compare and verify that your deco profiles are running similar???? Yes, I know, just stay in the water until they both clear.
Enough rambling, bye for now.
