Is the repeated appearance of a candidate's name on election ballots in the 2025 New York City mayoral election against the rules? No, that's not true: New York City Board of Elections staff told Lead Stories that those candidates are the nominees of two political parties. That can legally include running as the nominee of two officially recognized parties or running as the candidate for one recognized party and also as an independent.
The claim appeared in a post (archived here) published on X on November 4, 2025. In part, it read:
Mamdami listed on ballot twice in top row.
This is what the image posted to X looked like at the time of writing:

(Source: Lead Stories screenshot of post at x.com/OcrazioCornPop)
The entry implied that it is impossible or against the rules for the New York City mayoral ballot to list a candidate's name twice.
When a Lead Stories reporter called the New York City Board of Elections on November 4, 2025, staff there confirmed that if a candidate's name appears more than once on a New York City ballot, it means they are running as the nominee different political parties. In a follow-up call on the same day, another operator confirmed it, adding that it is not the first election in which it happened. The second person emphasized, however, that a voter can select a candidate only once under New York City's ranked choice voting rules (archived here).
In 2025, two contenders, Zohran Mamdani and Curtis Sliwa, appeared on the ballot twice, as a sample ballot for a Manhattan address from the website of the New York City Board of Elections demonstrated (click to view larger):
(Source: Lead Stories screenshot of page at the website of the New York City Board of Elections)
As seen in the screenshot above, Mamdani became a nominee from two parties, the Democratic Party (archived here) and the Working Families Party (archived here). Those are two of the four political parties officially recognized by New York City, along with the Republican and Conservative parties. PIX 11 (archived here) writes that such parties must gain at least 2% of the votes in the state's gubernatorial races to keep this status.
Parties that are not recognized are considered independent. Running from one of those would require filing a petition (archived here). This appears to be the case of Sliwa. In the 2025 NYC mayoral election, he ran as a Republican nominee, but also as an independent party's candidate (archived here) whose line on the ballot read "Protect Animals."