Royce Young at Daily Thunder astutely tweet at some of the pros at Operation Sports to hopefully find out what they thought about both the Thunder's alternate away jerseys as well as the apparent misspelling in their name, "THUDNER." Those guys had the knowledge and insight to actually investigate into it further. Apparently they employ someone called a 'hex editor,' a person who was able to dig into the game itself and pull out these alternate uniforms. Says Operation Sports:

Not fake :) Thunder mispelled seems to make it look like it tho. We have some hex editors at OS that found all of them.

Props to the experts for getting to the bottom of the authenticity of the alternate jerseys as well as THUDNER.