If the idea is to reload the data from Table1 into Table2 table (and then dropping Table1), then I'm not sure why you would need to do a "left join".
When loading Table2 using the resident load from Table1, make sure there is at least one differentiating field name/alias in Table2. If all the field names/alias are identical to that in Table1, QV will attempt to load them into the same table (i.e. Table1, and Table2 won't get created).
If you're wanting to keep all the field names/alias exactly the way they are from Table1, make sure to use the noconcatenate function before you load Table2.
load * resident Table1
group by Field1
order by ID;