The app name will never cause an app not to be installed. The package name is the important name.
It can happen if you switched between a different signing key, or if you have installed an app with a higher version code and then try to install an app with lower version and with the same package name. The same is true for targetSdkVersion.
The solution is to find the already installed app, which can have a different name as only the package name is important, and uninstall it.