PVT PLT IN AN SMA ACFT INADVERTENTLY LANDED ON THE WRONG RWY DURING A PRACTICE INST APCH.

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I WAS ACTING AS SAFETY PLT FOR AN IFR PRACTICE FLT. WE WERE CLRED FOR THE ILS 29R APCH AT SCK BY THE APCH CTLR AND TURNED OVER TO TWR. ABOUT 2 MI FROM THE RWY THE TWR CTLR CLRED US TO LAND. ASSUMING THE TWR CTLR GOT IT CORRECT; SHE SAID '... CLRED TO LAND 29L; TFC; AN XXX; DEPARTING 29R.' I HEARD '...CLRED TO LAND 29R; TFC...DEPARTING 29L.' I BELIEVE THE PF READ BACK THE CLRNC. THE RWY CHANGE DID NOT REGISTER WITH ME. THE CPR PLT NOTICED US ON SHORT FINAL AND ANNOUNCED HIS INTENTION TO WAIT ON US; AT WHICH POINT THE TWR CTLR ADMONISHED US THAT WE WERE NOT CLRED TO LAND ON RWY 29R. WE WERE AT ABOUT 100 FT AGL WHEN THE TWR TOLD US WE WERE LNDG ON THE WRONG RWY. THE LNDG WAS UNEVENTFUL. I BELIEVE THE FOLLOWING CONTRIBUTED TO THE INCURSION. PF: DID NOT RECOGNIZE THAT THE CLRNC TO LAND WAS NOT FOR THE RWY HE WAS APCHING. READ BACK THE CLRNC WITHOUT THINKING ABOUT IT. SAFETY PLT: ALSO DID NOT RECOGNIZE CLRNC WAS NOT FOR RWY STRAIGHT AHEAD. I DID NOT TAKE AN ACTIVE PART IN EVALUATING WHAT I HEARD. ALSO; DUE TO PAST EXPERIENCE; I HAVE COME TO EXPECT THE WORD 'SIDESTEP' TO BE A PART OF SUCH A CLRNC; AND WAS PROBABLY NOT PREPARED TO HEAR THE RWY CHANGE WITHOUT IT. TWR CTLR: DID NOT USE THE WORD 'SIDESTEP' IN THE LNDG CLRNC; WHICH WOULD HAVE CAUGHT MY ATTN; AND PROBABLY THE PLT'S. EVERY TIME I HAVE BEEN ASSIGNED A PARALLEL RWY; THE WORD 'SIDESTEP' WAS PART OF THE NEW CLRNC.