I think that it is fairly normal to have the left temps higher than the right. When driving a car, your right foot becomes much more sensitive as it is used to vary the throttle continually. Your left foot is used much more as an on-off switch for the clutch, and therefore has less finnese. I think that this translates directly into the anomaly you mention.
However, for the difference to be as high as 400degrees, suggests that you are braking too hard too early into the landing run. I rarely used to see temps greater than 450 degrees max on the A320 family, even at max weight, short runway high OATs. The energy disspated by the brakes is a function of the speed squared, so firm initial application will cause significantly higher temps. This is not to say that you shouldn't apply max braking at high speed should the need arise, of course, but try to minimise braking until at about 80 kts or so.