There are a couple of different reasons why it helps to create multiple connections for the same source service.
When you have multiple accounts
One common scenario is if you have more than one account with a service. In this case, you can set up a separate connection for each of your accounts.
Different sync rules for different projects
Another possible reason is the need to have different sync rules for different projects. For example, you might want to have your “Home Remodeling” board in Trello appear in your “Inbox” project in Todoist, but create individual Todoist projects for all your other Trello boards. Or you might also want to sync your labels for a certain Trello project one-way but keep a bi-directional sync for all other Trello projects.
How to set up multiple connections for one source service
To achieve this, simply navigate to the right-hand side of your dashboard and select the source service you want to create another connection for. Then, log in to the account you want to connect with your task manager and set up your desired settings for each connection.
Note: Before adding another account for the same source service, make sure you are logged out from the previously connected account. To do so, open the service in a separate window and log out from there.