Fabio's suggestion should work for you

INDEX ON MAX(DATE1,DATE2) TAG d12
SET ORDER TO d12 DESCENDING

>
>First i have a blank table with 2 fields: date1 and date2
>Append dates from a table called Table1.dbf:

>date1
>01.01.2000
>01.01.2001
>01.01.2002
>01.01.2003
>
>and then I have append dates from another table called Table2.dbf:
>date2
>02.01.2000
>02.01.2001
>02.01.2002
>02.01.2003
>
>for now if i give the browse command, my date appear like:
>date1       |  date2    |
>01.01.2000  |           |
>01.01.2001  |           |
>01.01.2002  |           |
>01.01.2003  |           |
>            | 02.01.2000|
>            | 02.01.2001|
>            | 02.01.2002|
>            | 02.01.2003|
>
>And I want the browse to appear like this:
>|date1       |  date2    |
>|            | 02.01.2003|
>|01.01.2003  |           |
>|            | 02.01.2002|
>|01.01.2002  |           |
>|            | 02.01.2001|
>|01.01.2000  |           |
>|            | 02.01.2000|
>|01.01.2000  |           |