Tableau can create multiple connections to a data source for many reasons including the fields in use, relationships to other data sources and the type of data source. I recommend reviewing the online help here for additional assistance in understanding Tableau data connections - Connecting to Data Sources - Tableau
If you have a specific concern and you are unable to create a Tableau workbook to share here, then please consider opening a Tableau Support ticket.
Also - please be sure to share the version of Tableau that is in use when submitting questions to the forums.
Thank You Patrick. Going forward will follow the same.