I don't know if this is a glitch or something.

I had good reputation with the NCR and the Legion (both at Liked) before I started theses following shenanigans: I killed Benny, return the Chip to Mr House, upgrade his Securitrons. Then I go to the Fort, blow up the robots, then I killed Caesar. At this point I'm marked as "Soft-hearted Devil" by the Legion, and was attacked on sight by Legion troops. Then I return to the Strips, killed Mr House and went on a massacre until I got Villified by the Strips. Then I attacked Camp Golf, the Dam, and also got "Soft-hearted Devil" by the NCR.

From then on I basically shoot NCR and Legion troops on sight, killed their Rangers and wipe out most Legion camps, but for some reason my reputation seems to be stucked at "Soft-Hearted Devil" instead of going down to Merciful Thug and then Vilified so they can send assassins and hitsquads after me.

Did this happen to anyone else? Is there a way to fix this?

That's the way the reputation works. http://fallout.wikia.com/wiki/Fallout:_New_Vegas_reputations has a chart with all of the rep types. You can only move right and down through the different reps(other than having your rep reset when you get the pardon).

It's not a glitch. After the NCR and Legion resets reputation earned never goes away. So since you were liked by both the NCR and Legion at one point you can never become hated or vilified since you still have some positive reputation with them.

That's the way the game works - you can't earn "negative" fame or infamy. They can only increase.

Check out the link provided by Spaceman "Ninja" Spiff.

Aww really?

I wasn't intentionally trying to get Liked by both factions. I need Liked from the Legion to get Legion Assault and key to their Safehouse for free Stealthboys. I got Liked from the NCR because due to all the Fiends bounties that get me caps and because the NCR gave a bunch of quests (And out of nowhere there's this one guy told me that I killed some Deathclaws and the NCR is grateful for it).

I'm way past the pardon points.... This svcks... Terrible design, IMO.

Since there's no difference in response I'm not sure why it was terrible design to simply give you a different title for your reputation.

Also you were intentionally trying to get Liked by the Legion and outside Quarry Junction you apparently deliberately ran missions for the NCR as well.

Im not 100% sure but I know my rep went from soft heart devil to merciful thug and villan before or something of the like

But then again I remember basically terrorizing a group but it never went down to villan so idk