A financial aid overpayment results when someone is paid money for which they are not eligible. It can happen if someone receives aid in two schools at one time. For example, a student cannot receive Pell from two schools at one time. Even if technically they don’t receive more than the allowed amount for the semester, it’s an overpayment - because one school must pay back the Pell to the government, leaving the student owing the school. Another thing that can happen is a student was paid Pell but later the school finds that the student was not eligible to receive the Pell. Regardless of whose “fault” it might be, the school has to repay the government, and the student has to repay the school.
If you have questions about what happened, email the financial aid office and ask for a detailed explanation of the situation.
“The college I went to was in the same los rios junior college family so I assumed they would know what the other junior college was doing.” Does this mean you did attend both schools at one time and received Pell from both schools? If so, you definitely had an overpayment. While you may have assumed the two schools would know, that is not how it works.