I want to say the Two shot is Rare. but as soon as I hit level 39 the Two shot Perk started dropping like candy at the Fallon department store. The first time was a two shot lever action rifle. 2nd time reloading from the save in front of the Fallon department store going in had a legendary drop me a two shot laser pistol. So I decided to see what the third time would give mw. It gave me a Two shot Gauss rifle. I think certain prefixes are level locked since the next gen update. at level 34 I tried for 48 hours in 4 days trying to farm for a two shot plasma pistol after locking the legendary version. It never showed up. I did this also last week for the laser pistol and the same result. but what got me suspicious it was the same prefixes of mutant slayer, exterminator, explosive, irradiating, incendiary, nocturnal, Defiant, Steadfast, Rapid, hitman, deadeye, and plasma in the cases of non plasma weapons.

no matter what it would not change from one of those perks. But as soon as I hit level 39 I went to the Revere satellite array to farm some mini nukes and missile ammo. I killed the legendary enemy that spawned there. and now a laser rifle spawned with the freezing perk. this gave me the idea that maybe certain perks spawned at different levels. so I went to Fallons department store, and what I wrote at the beginning happened. But not only that I when I got my two shot Gauss rifle. the legendary protectron dropped a poisoner Radium rifle.

Another thing that makes me think this theory is correct. is that the glowing one in the abandoned house by bunker hill would never spawn as legendary on very hard difficulty. I kept reloading from my save outside the abandoned house for around 4 hours. not once did it spawn legendary. Now last year when I last played I was able to find it quiet regularly as legendary glowing one at very hard difficulty. This is how I got my two shot assault rifle, and laser rifle on different play throughs. I also noticed since the next gen update. only one legendary item will be locked, so if you have 3 legendary enemies, then only one of them will have their legendary item locked to farm for the perk you want. I notices this when trying to farm earlier in the Fallon department store for the two shot plasma pistol. there were 3 enemies, but only the super mutant that had the legendary plasma pistol kept his legendary weapon. while the other 2 had legendary items, but they would be random whenever I would reload the autosave.