No law specifically prohibits you from filing for unemployment benefits with the same employer twice. You still must meet all eligibility requirements for a successful unemployment claim, including length of service and gross wages. Lying on an application for benefits to gain eligibility for unemployment benefits or a higher benefit amount is a crime which can cost you your unemployment benefit eligibility and land you in jail if you have prior offenses.
You must secure employment twice with the same employer and work for the requisite amount of time in your state to receive unemployment benefits on two separate occasions. You must also accumulate the minimum earnings in two different time periods to successfully file for benefits. Nothing prevents you from filing for unemployment benefits, even if you don't meet the eligibility criteria, though your state's unemployment division will probably dismiss your case.
Your ability to file for unemployment twice with the same employer may rest on how long you were on unemployment the first time. The total length of time you may collect unemployment benefits varies by state though usually falls in the 26- to 30-week range depending on the nation's unemployment level. If you reach your benefit maximum during your first stint with an employer, you can't file for benefits again during the year whether or not you meet all other eligibility criteria.
Labor unions regularly rotate union employees from active duty to layoff lists so unions can keep as large a number of workers on the employment roster as possible. If you're a union member, you may return to active duty for a specific amount of time so you earn enough in wages to regain your eligibility for unemployment. Once this happens, the employer lays you off temporarily and "rehires" another union member to take your spot. This enables more workers to achieve a full-time income and avoid outright layoffs.
It is illegal to obtain unemployment benefits by deceit or purposeful entry of false information to artificially inflate the benefits you receive. You must answer questions regarding your termination and earnings truthfully when you apply for benefits. Failure to do so could result in your state's unemployment division banning you from filing for unemployment benefits for a specific amount of time. This could damage your finances if you legitimately lose your job while still under the ban. You must pay back any unemployment benefits paid to you in error, plus interest.