Right-click the selected model and choose File actions > Duplicate from the menu.
Or select the Models > Duplicate model menu option.
Or click 
in the toolbar.
Enter details for the new model.
New model number — Model number identifying the new model.
Reference model — Number of the model serving as the reference.
By default, this will take the name of the original model selected for duplicating.
Model description — Brief description for the new model.
Use final parameter estimates from reference model — Check to copy parameter estimates from the original model.
Press the Duplicate button to create the new model and open it in the editor.
Multiple duplicates of multiple NLME models
Creates multiple duplicates of multiple model files, with (optionally) updated run/table numbers and final parameter estimates.
Select the Tools > Batch operations > Create n duplicates of model(s) menu option.
Or click 
in the toolbar and select Create n duplicates of model(s).
Enter duplication details.
Duplicate models — Select the model(s) to be duplicated.
Number of duplicates — Number of duplicates to create for each selected model.
Specify the procedure for copying.
Change run-numbers in output/tables — Check to incrementally update the run numbers for each duplicate.
Use final parameter estimates from reference model — Check to copy parameter estimates from the original model.