It will work but....
When you change one mix. You will lose the pressure on the other can and therefore it will have to start up again (they dont keep the consistency then.)
What I got was a 2 way gang valve from Pets at Home for £1.29 which lets you put 2 inputs in and one input out. (Its made to be the other way round i.e. to split 1 air pump to 2 air stones but works the opposite way round.)
You can close the valve on the cannister you are changing therefore maintaining the pressure on the other cannister.
Go away put in new solution, reconnect and reopen the valve and hey presto. The can that you are not changing keeps its pressure. doesn't have to start again and you keep a better consistency.
Andy