Yes, you may upload more than one application! Ensure each application has its own unique package name, as set in the AndroidManifest.xml.

Note that if you do insist on uploading multiple applications at once, avoid submitting more than half a dozen over a short period of time. Though your applications will eventually be reviewed, multiple submissions in excess will receive a lower priority review status and may not be reviewed within the normal timeframe or for extended periods of time.