Mike,
When you say "..small differences in adjustments..." you mean the spanner nut on the bottom of the shock tube that pre-loads the spring, right? It's not unusual for springs to "wear in" a little differently based on both static & dynamic loads over time, and that's the beauty of the spanner nut adjustment to account for those small differences over time. I would hope that new springs would be pretty close to the same though.

Back in my Navy days we had a sand crab (civilian working on base) fuel truck driver that must have weighed 400#. Saw him driving in an old '56 Chevy beater one day, and it must have been 2" to 3" lower on the drivers side running down the road, but then he pulled into a parking lot, got out and it still sat 2" to 3" lower!!