When trying to deploy a new package with the K2 P&D tool, the following error is shown:
'An item with the same key has already been added'
The error will occur at the package deployment step.
If you look in the Hostserver logs, you will notice a more descriptive error message:
"DeploymentServer","30003","DeploymentError","SourceCode.Runtime.Services.Forms","30003 An item with the same key has already been added."
This is a known issue within the K2 Product.
There is a fix for this issue in K2 4.7 - please contact K2 Support for this fix.
This issue will not occur in newer versions of K2.