Data Validation thru Double Input into Field

I have to input data into "ANYDATA" field. Since I need this input to be 100% accurate, I would like my operator to input it TWICE. E.g. 1st input - Obama 2nd input- Obama. Only if BOTH the entries match will the data move into ANYDATA field, else the field becomes blank once again, and the operator has to re-key twice again. In example above, if he had input 2nd time as Obame, then he will have to repeat the process. Can anyone pls help me create suitable formula/ field settings...Thx! Preferably, I would NOT like to create two dummy fields "ANYDATA1" and "ANYDATA2" with corresponding entry in "ANYDATA" if both match.

p.s. Need this to be done using MS-Excel only.