Hey Sean-Paul! From what I've gathered, the game was only released in Europe. The naming is pretty confusing, with some places listing "Power Play Tennis", some listing "Tennis Masters", and the one you found listing "Tennis Masters Deluxe". Game screen shots of the various versions look similar though, and you can see Martin and Brian as names in the scoreboard images in them. :)

https://www.video-games-museum.com/en/game/Tennis-Masters/81/5/29704/boxarts

Maybe when the Codemasters publishing agreement was complete, the System 3 developer/publisher re-released an updated version of the Mermaid Studios game? It's a new mystery to chase!