Axolotl need excellent water all the time to stay healthy and it often requires daily water changes as I understand they are messy eaters and when the bigger they are, will be big poopers, eat lots of things if they fit in their mouth.
Thinking that it would be more trouble /difficulty setting up 2 sides completely different in 2 halves, double pretty much everything as the care wouldn't be the same, and would not be advisable to share the water and filtration, imho.
An appropriately strong gorilla shelf /rack maybe and having 2 tanks stacked if you have a space issue otherwise I would think 2 tanks would be easier to maintain separately.
Also I feel like 2 feet x 1 foot foot print - half the standard 55G, wouldn't really be enough room for a full grown, properly cared for Axolotl. Girl at our CAS has one which is 10-12 inches or so long and body is bigger around than the average apple.
Many of the Axolotl don't live long enough to get really large. Often due to improper care.
You could do a really nice natural habitat styled tank 3' or more. 40G breeder would be a nice size. Wide foot print, lots of moving around space.
