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But he was not named as a 'Designated Player' in their squad list - meaning he was earning more than allowed.
Clubs in the MLS are allowed three 'Designated Players' that don't count towards the salary cap and failing to register Matuidi means Miami were operating with four.
The rule came to be after Beckham's lucrative transfer stateside in 2007, when he left Real Madrid to sign for LA Galaxy.
Miami have also failed to register former defender Andres Reyes correctly and it has seen managing owner Jorge Mas hit with a $250,000 fine.
In addition, the salaries of Leandro Gonzalez Pirez, Nicolas Figal and Julian Carranza were not fully disclosed.
Beckham himself as well as other owners have been cleared of any wrongdoing, as have any players.
An official statement MLS commissioner Don Garber read: "The integrity of our rules is sacrosanct, and it is a fundamental principle of our league that our clubs are responsible for adhering to all league regulations.
"Our rules will not be compromised. These sanctions reflect the severity of Inter Miami's violations, should encourage complete cooperation by all parties in future investigations, and will serve as a deterrent for clubs from violating roster rules."
Mas released a statement on behalf of Miami also, which says: "Inter Miami CF acknowledges that the Club violated Major League Soccer's roster rules in our first season.
"We have worked closely with MLS to address these issues and have made significant changes in our management structure.
"Following our inaugural season, we took a deep look at our soccer operations leadership group and made decisions that not only strengthened our internal roster compliance measures, but also better positioned us to build a sustainable, long-term competition strategy with the hiring of Chris Henderson as Chief Soccer Officer and Sporting Director in 2021.
"Inter Miami is an ambitious Club with big aspirations. We believe our fanbase, market and ownership group propel us to be one of North America's most-followed futbol teams in the world. We are committed to supporting our team and building a roster we are proud of."
Inter Miami, now managed by Phil Neville, currently sit seventh in the Eastern Conference and lost their last game 1-0 to Chicago Fire.
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