They can't be exact, but using the same gauge they can be ± 1-2 psi which is not enough to cause an issue. With the differences in road surfaces and suspension movement they are always changing pressure anyhow.
That same risky logic is what happens in a corner with them plumbed together. The volume of air in each bag changes, and when the truck come out of the corner the pressure between the two bags is different until the 1/8" line can equalize the volume. This is where body roll isn't decreased, and potentially increased after a corner.