Crossing duplication in Australia

 https://www.bridgeweb.com/Work-begins-on-Australian-estuary-crossing-duplication/9335

https://minister.infrastructure.gov.au/c-king/media-release/work-starts-mandurah-estuary-bridge-duplication

https://www.bridgeweb.com/Contractor-picked-for-Australian-bridge-duplication/9222

https://en.wikipedia.org/wiki/Joy_Baluch_AM_Bridge#Bridge_duplication

https://www.dit.sa.gov.au/infrastructure/road_projects/joybaluchAMbridge

https://www.abc.net.au/news/2023-03-16/joy-baluch-bridge-duplication-opening-port-augusta/102097006

https://www.mainroads.wa.gov.au/projects-initiatives/all-projects/regional/mandurah-estuary-bridge-duplication/

https://roadsonline.com.au/was-110m-mandurah-estuary-bridge-duplication-fully-funded/

https://www.buildingfortomorrow.wa.gov.au/projects/mandurah-estuary-bridge/

In the USA, bridge & tunnel duplication is called twinning.

https://en.wikipedia.org/wiki/Crescent_City_Connection 

https://historicbridges.org/bridges/browser/?bridgebrowser=louisiana/greaterneworleansbridge/