This error occurs when the defined description already exists in the code.
Where ‘%s :'%s' - Definition Type - Definition Name %s(%d)- Previous declaration path(Line Number of Previous Declaration) .
Rename the duplicate description or remove it to avoid the error. It is always a good practice to prefix definition names with organisation name or any other, so that it doesn't conflict with the definition declaration in default code.
Example
[#Menu: Gateway of Tally]
Add: Item: ($$LocaleString:"Config"): Menu: Configuration
[Menu: Configuration]
In the above example, a Menu called Configuration is defined which is already exists in the Default TDL code. Hence the message error T0009: Menu - 'Configuration' is a duplicate description already defined in ..\tdl.template\src\config\iniconfig.tdl(9). appears.
The above code is corrected by renaming the menu definition as shown below:
[#Menu: Gateway of Tally]
Add: Item: ($$LocaleString:"Config"): Menu: TSPLConfiguration
[Menu: TSPLConfiguration]