Slenk, two different lots of cast bullets? If so, are the lengths of the bullets the same? If so, then it's just probably the composition of the bullets that make the weight difference, if so then load them the same. The little weight difference won't make much difference unless you're doing competition shooting. If there is a length difference, then seating them to the same OAL will decrease the space inside the shell, which will increase the pressure inside the case with the same amount of powder. As long as you're not loading max loads or near max loads with them, you'll be OK. I don't think that the length difference will be that much to even worry about with the exception of max loads of course.