Every android application file – apk has two main things:
- package name – (unique id of app like com.example.application)
- signature
More information about the second. Every apk file should be signed with developer keystore. If this is the debug version it could be debug-keystore.
In this keystore there are some information about developer and other information.
When you install application android system at first checks package name – whether or not this application have been installed already. And if so system checks signatures. The signature of installed app and app to be installed must be the same. Otherwise you will get error, you describe in your question.
So, the answer is: not, you can't install another application with the same package name if the signatures of installed and to be installed apps are different.
You must uninstall previous version and install new version, if you need new version.