There are a couple of ways to copy existing models. They differ in the aspect of what is copied.
When copying models it is not necessary to define all the model properties. Most of the properties are defined by the original model and are not modified for the copy.
The first way to copy a model is similar to the creation of new models. Either right-click the model in the Tree View window and select Save As or open the model to be copied and select File→Save As. A Save As New Model dialog is displayed. There you can define the logical and the physical name of the copied model. You can also define the library to which the copied model will belong. All other properties are taken from the original model and cannot be changed. You can find more detailed information about these properties at Create new models.
Once you have defined all the necessary properties click the OK button to create a copy of the model. As with the creation of new models, MLDesigner checks for the existence of models with the same physical or logical name saved in the same location.
The second way to copy a model is to drag a model to any directory in the Tree View and select Copy. See Copying, Moving, and Referencing Models for further details.
There is a very important difference between Save As on the one hand and Copy on the other hand. Save As copies the model directory and only files which are necessary to describe the model, these are makefile, mml and pl file. Copy copies the model directory including all files and subdirectories.