From 8.48 tools version creating two records at root level is not possible. This will be achieved using Container Message.
Container messages: A container message is a Non RowSet-based message that holds one or more part messages. A container message must contain all RowSet-based messages or all Non RowSet-based message parts.
Grouping one or more part messages into one is container message
Main Menu >> People tools >> Integration Broker >> Integration Setup >> Message
The above message is the main message used in publish or subscription people code its equal to having two records at root level.