I agree with Bill and respect his judgement and experience. Listen to what he says.
That said, if you travel single rental 80's may be the only option. In that case a set of travel bands and independent double may make sense for a diver with a high SAC rate (although you also need to assess why you have a high a SAC and work on resolving the problems that result in it being excessive - don't use more gas a crutch to avoid fixing the problem.)
If you are going to use independent doubles, manage them correctly. The only acceptable method that will keep you out of trouble is to:
1. Breathe 1/3rd of the first tank, then
2. Switch to the second tank and breathe 2/3rds of it, then
3. Switch back to the first tank and breathe the second 1/3rd of it.
4. Leave the last 1/3rd (1000 psi for an AL 80) in each tank as a reserve.
Number 4 seems overly conservative but 154 cu ft is a lot of gas even for a hoover and with that much gas you need an ample reserve for the depth, time and/or deco induced problems that could result.
Managing in that fashion will require an SPG on each tank. Using the elctronic transmitter on one of them is probably ok (I am not a fan of air integrated wireless computers on general principal as they are much more likely to fail at several points), but trying to use two transmitters and switch back and forth is overly complicated, complicates the two gas switches you need to make and is far harder than just using a normal SPG on the second tank clipped off on that side of your body.
And as Bill said, don't dive with two separate mixes - that is a fatality waiting to happen, especially when they are both back gas where you cannot directly verify and confirm the mix you are switching to.
It is possible to end up with a couple of rental tanks a percent or two off (both may nominally be 32% but one may be 31% and the other may be 33%) In that case program the computer with the lowest mix for the most conservative deco plan and then do the dive with the shallower MOD for the highest mix. If there is more than a couple of percent difference, reject one or both of the tanks when you analyze them at the rental counter or fill station and get two that are in the same ballpark.