Dear Mufti Sahab.
Assalamualaikurn Wa-Rahmatullahi Wa-Barakatuh,
Our Masjid premise was acquired about 20 years ago۔It used to be a single dwelling house. Alhamdulillah. Our community grew by time and concerns regarding possible collapse of wooden structure of the house when community events, such as Jumu'a Salaah took place, lead our masjid shoura to decide to have two Jum'a salaats.
By the Grace of Allah Subhanahu Wa-Ta'ala, our community was able to build new Masjid structure at the same place. The city however gave permission for a maximum of 256 people to be allowed in the new building at any given time. Their permission was based on the number of parking places masjid has. The responsible individuals of the masjid signed this agreement to get the masjid affairs rolling.
Prior to moving in to the new Masjid building, The shoura decided to continue with two Jumu'as based on parking limitations and agreement with the city. A concern however was raised by the main Imam at that time that the new Masjid building is big enough to accommodate people of both Jumu'as and that it is against the Shariah to hold two jumu'ah in one masjid unless there is pressing a need to do so. The shoura decided to review this point after a six month period.
The matter was taken up almost a year later and the shoura decided to stop the second jumu'ah following the spring time change. The reason that was given to the musallees was that it is against the shari'ah to hold two jumu'ahs in one masjid. When people ask "what about the agreement with the city"? which If violated can potentially bring their wrath in the form of closure etc. The answer that is given is"لا طاعت مخلوق فی معصیت خالق"i.e. one should not obey the creation in disobedience of the Creator.
The question to you is, under the above conditions. what is the status of the second Jumu'ah if it is held.
Any Masjid Management is responsible for negotiating any legal issues pertaining to the masjid between the Masjid and the city.
If there is any chance of extension of the legal ordinance and there is space available in the masjid for more Musallees, then it is better to hold one Juma instead of two Jumas.
Also if there is another masjid available in the same locality then two Jumas can be schedule in such a way that can accommodate both communities.
If such options are not available and there is no more space available for Mussallees or if there is any chance of the Masjid being shut down because of legal actions, then under these special circumstances, 2 Jumas may be allowed in the same Masjid in Shariah