There is a feature in Workbench that allows you to change the package name by selecting and then clicking again on it.
Here is a package name after clicking just once to highlight it:
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But, this can be prevented. In Administrator Tool if you navigate to the project and state your package is in, and right click on the Package name and select “Properties” and the “Access” tab, there are 2 access lists associated with states. The “Update” access list controls which users have permission to update the properties of the state (name, list of processes, etc). The “Update Package” access list controls which users have permission to update the properties of any packages in that state – including the package name. If you remove user groups from the “Update Package” access list, then they can click on the package name all they want and it will never go into edit mode, thus preventing the UPDATE_PACKAGE transaction and the change in the Modified Date.
To read more about access permissions, and which types of access control which actions, read the "Control Object Access" chapter of you SCM Administrator Guide.