Illogical damage count?

I had basic knowledge of versus fighting games, but never tried to play one seriously (first experience was with SF4 on Xbox 360 and pretty confusing). I loved Skullgirls's graphic style, so I decided to buy it with the recent Steam discount and I enjoy trying to chain combos in training mode (the lowest level AI still crushes me, though).

I spotted an odd thing while playing Ms. Fortune: a 9 hit combo damage total (as displayed in the training mode) is lower than a pretty similar 8 hit combo. The base combo is Standing Low Punch → Standing Low Kick → Standing Medium Kick (2 hits) → Crouched High Punch (Launcher) → Aerial Low Punch → Aerial Low Kick → Aerial High Kick.

I tried squeezing another Standing Low Punch at the start to do one more hit and potentially more damage, but the final result is 2844 for 8 hit combo and 2812 for 9 hit combo. Damages are adding consistently (8 hit total < 9 hit total) until the final Aerial High Kick.

Is it a feature? Or a glitch?

Subsidiary: is it worth adding an air dash cancel at the start of the aerial part of the combo to do one more Aerial Low Punch?