It happens because keystores on your laptop and original pc are different. it’s called debug.keystrore and located in
%USER_HOME%/.android/ folder. TO be more specific it happens because eclipse tries to push apk with reinstall key. So you have two options:
- Share debug.keystore between various development pc’s
- Manually uninstall your apk from device ( using adb )
The simplest way is to Uninstall the application from your mobile if you load it already.