MR results history

Dear Experts,

Is there any possibility that i can found the over written Meter reading results,

Example: if my periodic MR reading is on 20.4.2011 is 200 units, but due to some reasons it was changed to 220 units,

now i want to find the MR reading of 200. from which table i can get this over written MR.

or there is no record saved for over written values?

any body have clue in this,

thanks..