Two Jummahs in one Masjid is not allowed according to the Scholars unless there is a need such as lack of space etc. Otherwise, it opposes the Shariah and the guidance of the Salaf of the Ummah..
Shaikh al-Albani rahimahullah said:
“All praise is due to Allah that they do not fall into the likes of this opposition of praying a second Jummah in one masjid as is they do for the Eid prayer in the Masaajid in some Western lands (in) which the Islamic community is such that the Masjid is not spacious enough for those who arrive for the Eid prayer. So, they are forced to establish a second congregation and sometimes a third also because the Maasjid are not spacious enough and the streets there are not there places such that they can block them for prayer as occurs in Muslim lands. This is because these are the lands of the disbelievers and misguidance. The point is that the Muslims, all Praise is due to Allah, preserve one congregation in the Masajid with one Jummah prayer. This is what the later generations inherited from the Salaf…”
[Fatawa Juddah no. 9]
Faisal Ibn Abdul Qaadir Ibn Hassan
Likewise, the Permanent Committee said in regards to having two Jummahs in one Masjid in France:
“Offering the Jumu`ah Prayer twice in the same Masjid has no precedence in Shari`ah (Islamic law). The original ruling is offering one Jumu`ah Prayer in the town, unless there is a legitimate excuse, such as people living great distances from the Masjid, the narrowness of the first Masjid, or a similar excuse. In this case, another Jumu`ah Prayer is offered in a suitable place. The questioners should seek another place to offer the Jumu`ah Prayer, even if it is not a Masjid, such as a house, a garden, or a public square where the officials allow the Jumu`ah Prayer to be held.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family and Companions.
The Permanent Committee for Scholarly Research and Ifta'”
And Allah knows Best