Savage Blow's top and bottom hits do same damage

So, I tried using another Dagger on Bounzy the Bandit, using the Fruit Knife you get after getting Rogue status. What happened was that my top and bottom damage were different, I started to think, maybe it has something to do with Cassandra's rental weapons or weapons she gives out.

I went to get the rental weapon for my Shadower, asking for 100 Beakers at Homuns. Viewer discretion is advised:



Screenshots were taken in order, from left to right. On the mobs I tested inside the Zenumist lab, I got the same damage on the top and bottom hit of Savage Blow using my Golden Double Knife (GDK) and Fruit Knife (FK). So, I went to test it over at Scorpions with my GDK and... the hits were different.



I decided to go use my Fruit Knife at Scorpions. The hits were the same for about 70% of the time, the other 30% they were different.



**Summary:

On Bandit,
- Scorpions with FK, hits are different.
- Scorpions with Explorer's Bazlud, hits are the same.

On Shadower,
- Mobs inside lab with GDK & FK, hits are the same.
- Scorpions with GDK, hits are different.
- Scorpions with FK, hits are same around 70% of the time.

Guys, what the fuck is going here?