Pension Audit Is It Illegal, Will The IRS Fine Or Audit Someone Who Declares Two People Using Same SSN....?

Is it illegal, Will the IRS fine or audit someone who declares two people using same SSN....? - pension audit

I know many people here in Texas, the "her" family "borrow" your Social Security number and report, as it has the 2 positions? I believe that the IRS does not see anything unusual when the same people at the same time two different locations, one at-bat? Or Legall and SS benefits, including any increase in pensions so its ok?
The experts help please!