To switch channel managers, you should first disconnect your listings from your channel manager, and then disconnect your Airbnb account from it after.

Disconnecting listings from channel manager:

Go to your Listings page
Select listings by ticking on the tick-boxes on the left of each listing
Click on "Edit Selected" o
n the top right of the page
A left panel will pop up.
Scroll to find Sync Settings
Click on Disconnect

Disconnecting Airbnb account from channel manager:

Go to your Account Settings
Select Privacy and Sharing
Under Services, click on "Remove Access" found beside your channel manager

This is probably because you did not merge your listings after connecting them to your software.

This is a mandatory step for when you have an existing manual listing on Airbnb, and you are connecting it to your software.

You would need to merge both listings together to prevent having duplicates for the same listing.

This will not be done automatically as you would need to log in to complete this step before you hit publish. We would advise to delete the new listing and restart the listing connection process if you encounter this issue.