To the best of my knowledge, the grains listed in BeerSmith represent commercial suppliers specifications for either a particular lot or a target specification. Multiple entries may represent grains from different maltsters. While they are relatively close in most cases, I would not count on them to be 100% accurate for any one item.
I always get the latest tag information from my LHBS for the grains that I buy and update them. Being an agricultural product, the information changes from lot to lot and from year to year, not to mention supplier to supplier.