It might help you get an answer on what you have in that mystery box if you post 2 photos of each of your 2 rounds ... 2 showing the whole rounds from the side and 2 showing the head stamps. People "skilled in the art" would be able to tell a lot from the shape and construction of the bullets ... even just by the picture. For one, we would be able to see if it is even possible that they are actually the same round, hidden in two different boxes.
It would also be interesting to see measurements of the overall length of the rounds ... taken with a caliper, not a ruler
... while you might not be able to tell exactly what the weight of the bullets are by the weight of the cartridge, if these are factory loads from the same company (i.e. using the same brass), then there won't be 30 grains of difference in the powder charge ... so we might be able to rule out 150's and that is what you think you have.
Do you have access to a reloading scale? Even if your scale is good for 0.01 oz, that is a tad more than 4 grains ... it would be better to have a more accurate tell on the weight of your cartridges.
Saands