<human>: Preface:
1. I am asking on behalf of my girlfriend, who either is afraid of Reddit or too lazy to sign up.
2. The location is in Pennsylvania, USA.

My girlfriend signed a lease for her apartment with Property Management Company #1 (PMC1) in May 2015, putting down a security deposit of one month's rent ($2,300). In late 2015, PMC1 merges with Property Management Company #2. PMC1 is seemingly managing the maintenance of the apartment, while PMC2 is managing the financial side.

PMC2 doesn't seem to be particularly well organized. They made a number of mistakes in the past few months, including losing a rent payment check that my girlfriend delivered personally.

So GF renews her lease in May of 2016, and is required to pay a security deposit again. Her rent increased to $2,350.

Today, she received her refund for the first security deposit, except it is $2,800 instead of $2,300.

Is this something worth coming clean and fixing? IANAL, but the way I see it, this is their mistake and their problem. But GF is seemingly a better person than I am, so she's hesitant. Can PMC2 pursue any legal action if this eventually noticed but had never been corrected? Or would they just clawback the money?

Any help is really appreciated!

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Girlfriend got a $2,800 security deposit refund on a $2,300 security deposit from a property management company that doesn't have their shit together and wants to know what to do.