Why is everyone comparing duke nukem with serious sam?

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Serious Sam 3 BFE just came out and each time I watch a walkthrough with serious sam 3 on youtube everyone is commenting serious sam rocks the hell out of duke nukem and the same in duke nukem games. Are they from the same company? Like serious sam 3 is from croteam but duke nukem i think its not a part of croteam. Thanks for reading and commeting :)