Four distinct 8-bit integers
JavaScript (Node.js), 35 31 27 23 bytes

-4 bytes thanks to Arnauld and Kevin Cruijssen

-4 bytes thanks to xnor



a=&gt;b=&gt;[c=3^a&amp;1^b&amp;2,c^4]


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Explanation:

Takes the flipped 1 bit of the first number, and adds the flipped 2 bit of the second number, guaranteeing a number different from both inputs in the 2 least significant bits. Outputs this number, and 4 added to this number