How function logicfornextid generates new id? Do you get duplicate Id's on the same PC or between different PC's?

>This is my function I have a global variable (m._lstuid) which stores the last gen id and the next gen id is first compared with the stored id so as to avoid duplicates on a fast machine, but it still gens duplicates

>FUNCTION nextid
>   m.zresult = m._lstuid
>
>   DO WHILE m._lstuid = m.zresult
>      m.zresult = logicfornextid()
>
>      *** I had to put this to stop duplicates and I hate it
>      *** WAIT "" TIMEOUT 0.001
>   ENDDO
>
>   m._lstuid = m.zresult
>
>   RETURN m.zresult

>
>what am I doing wrong, why do I still get duplicate??????
>
>Thanks in advance.