I hate to inform everybody that brass weight doesn't necessarily mean that case capacity is the same.The weight can change in the same batch of brass just because of the density of the brass stock being used.It looks like you have a batch of brass that has been formed at a transition point in the brass stock being used to form that batch.The capacity may be identical across the board,even though it is heavier in some and not the other.The only way to check is fill a case with the powder you normally use to the top of the neck,tap it on the bench to settle it,top up if necessary,and weigh it.
Do the same with all your cases that show big differences in weight,and see what the difference is.
If it is 1 grain or less,you won't have any accuracy problems with that brass,but if it is more than 1 grain,I would set those cases aside for working up purposes only,and keep the others for serious target/varminting work.
Too many people believe that case weight has a direct bearing on case capacity without actually checking how much difference there is in actual capacity!
Any metal can have the same recipe when being made but some ingredients can be heavier depending on their origin,brass included.
I discovered this a long time ago,when balancing crankshafts from the same companies,their steel weights varied significantly depending on where they sourced their stock from,even though it was all 4140 steel.
Sorry to be so long winded.