A doubles round robin works like the singles version, but the entry is a pair rather than an individual: each pair plays every other pair in the division once, and standings rank pairs.
Pairs and partners
Both partners are named on the competition entry. The event's entry policy controls whether a player may enter more than one doubles division and whether the same two players can appear together in more than one entry.
Substitutions
If a partner becomes unavailable, the organizer can approve a substitution under the event's published replacement policy. Official results stay with the pair as it stood when the match was played.
Ratings
Doubles results feed each player's separate doubles rating — see singles vs doubles ratings.
Sports Axiom events follow the standard rules of tennis unless the organizer publishes event-specific modifications on the event page. The International Tennis Federation is the rules authority for the sport itself; Sports Axiom links there rather than reproducing rulebook text.