Starting with Terraform version 0.7.3 you can only define a variable once within a directory or a module. Before that release you could copy variable definition files from other modules and did not throw an error if you had the same variable defined in multiple files within the module.
In the new version of Terraform if you define the same variable name multiple times within the module you will get the following error message,
Variable '...': duplicate found. Variable names must be unique.
Make sure a variable is only defined once in the module or directory.
