SSIS 2012 item with same key as already been added error

I am in the process of converting an existing SSIS solution that I use for my demos. I converted my packages to project (SSISDB) deployment model as opposed to package (file system) deployment model. While doing the conversion, I encountered the following error when I tried to save one of my package.

Pressing on OK led me to the following error message:

I had hard time figuring out what was causing this error. Then, reading the first error message, I looked at where in my package I might have used the same name. It was not obvious but I noticed that I had previously converted connection managers of a package to project connection managers. Then, when I opened my other package, I had duplicate object names

• cmgr_DW package connection manager:

• cmgr_DW.connmgr project connection manger.

Project connection managers are assigned to all packages in the project. I deleted the package connection manager in my package I tried to save:

And the project connection manger appeared replacing the package one with the same name.

I did the same for my other package connection manager and I finally been able to save my package in the project.

In conclusion, connection manager’s name must be exclusive between package and projects. You can use the same name for package connection managers across many package but they cannot conflict with project connection managers. This makes a lot of sense when we think to it but the error message not obvious to decode at first J.