Hi mch,
There is more about the different ways that one mattress can “match” another one in post #9 here but depending on the specific changes you made or which layers you “shaved” in some cases even what seem to most people to be relatively small changes (especially to the comfort layers) can make a surprising difference in the feel and performance of a mattress. In most cases a mattress that has thinner comfort or transition layers than your “reference” mattress will feel firmer and somewhat less “adaptive” to your body profile in different sleeping positions.
There is also more about the adjustment and break in period and some of the variables that can affect the feel of a new mattress compared to what you tested in post #2 here (or in post #2 here if it also contains memory foam)
It’s less likely that the mattress is different from what you ordered and more likely that the mattress tag was for the prototype that was tested for the fire regulations since most manufacturers prepare a batch of tags ahead of time and wouldn’t print a different tag for every variation that was possible inside the same basic prototype. You could confirm this by comparing your tag to a mattress tag on the “standard” mattress that you tested in the showroom (before the customization) which would likely be the same (outside of the manufacturing date because the floor model may be from a previous batch).
Phoenix