Duplicative petitions filed by an employer for an employee in the same fiscal year will be denied or revoked. In certain limited circumstances, even multiple petitions filed by unrelated employers may also be denied. USCIS may retain all the fees, and either deny or revoke the petitions, if multiple petitions by the same employer are noticed by the USCIS. The petitions will not be returned to the Petitioner. Multiple petitions by the related companies are also prohibited unless a “legitimate business need to file an H-1B on behalf of the same alien” can be demonstrated. This rule was enacted “[t]o ensure a fair and orderly distribution of available H-1B visas.”

This regulation does not prohibit employers from filing H-1B CAP petitions for employees whose H-1B CAP petitions were selected but was either denied or are pending adjudication or is pending Appeal or under a Motion to Reopen status. An employer may file subsequent petitions on behalf of that employee in multiple fiscal years as long as the employee is still subject to the H-1B CAP. For example, if an H-1B CAP petition was selected in the fiscal year 2018 but is still currently pending with USCIS, the regulations do not specifically prohibit employers from filing duplicate petitions in the fiscal year 2019.

https://www.uscis.gov/archive/archive-news/questions-and-answers-uscis-announces-interim-rule-h-1b-visas