In this case, this is normal behavior.
You need to be careful with the sections of the screens you are trying to compare.
Firstly, the LOC by technology is only a subset of the current technologies in the snapshot, so if you have a large amount of technologies you will not see them all show up.
Secondly, any technologies which are no longer part of the snapshot will not be listed here. Items which have a 0 LOC for the current snapshot but a value for the prior snapshot will not be listed, so the numbers are expected not to add up in this case for the prior snapshot as the focus for this section is technologies in the current snapshot.
If you look at this screen for the prior snapshot, you can see what those technology results and values were for that particular snapshot.