Making second jamaat in the sehen of the musjid

In some masjids, there is a seperate entrance, like a connecting room, before the main praying hall, where people keep their shoes. The doors of the masjid first open into this entrance, and then there is another door to the main praying hall where the imam leads the salaah. Often this area is carpetted for praying. Is it allowed to make a second congregation (jamaat) in this entrance?