It is a ruling that we cannot make second jamah in the masjid where Jumuah salah is performed, but I want to ask that can we make second jamah at the second floor of the masjid where Jumuah is performed or it is not allowed to perform second jamah.
بسم الله الرحمن الرحيم
(Fatwa: 936/587/L=1434)
In principle a land dedicated formally for salah is mosque from the earth to the sky; hence the ruling of second jamah in lower floor shall be applied to the second jamah in the second floor i.e. it is makrooh.
Note: You may offer second jamah in the outer portion of the mosque.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband