Unless you have torsion axles? the equalizer (center pivot) on tandem trailer axles equalizes the loads between the two axles...even if slightly off.
Actually the equalizer bars allows the axles to step over humps and dips independently but don't fully equalize the load between two axles.
I attended a seminar put on by Kaufman equipment trailers some time ago for their commercial customers about the difference in axle loads if the trailers deck wasn't level and axles were weighed separately..... and other pros and cons of running with a level/unlevel trailer.
They had different size trailers with different hitch to the axle distances which made the most differences in F to R axle loading. Trailers like rvs with axles closer to the hitch showed greater rear axle load differences than a same size trailer with axles placed farther aft. Example would be a 36' tandem axle 5th wheel trailer vs a 36' equipment trailer with axles much farther aft.