File for a correction. Demand it.. Last year i discovered, somehow my S.S. contributions where double what they should have been, I called S.S.I. they were totally useless and clueless as to why this happened, i called my accountant, he said " dont worry about it," all i can assume is someone was using my S.S.I. number and where making deposits into my account.
It doesn't do any harm to have more going in because someone else is using your SSI. If that is the case though (and not just an accounting error), they may have stole more of your identity than just your SSI#. And if they ask for SSI benefits using your SSI# then it will be a mess to clean up when you want to get those benefits for yourself.
They may have also opened credit, banking, etc., in your name, so check your credit report for accounts you did not open. Taxes too. I have a friend that had someone steal his identity and file for a tax refund/etc. using his identity. He keeps having to deal with this every year for years now and it still is not resolved. A real mess because he is married and his wife runs a business so they file jointly.
Then there is the possibility that they have warrants out for them using your identity.
So don't just let it ride - the SSI might just be the tip of the iceberg.