Add fields to existing internal table and collect statement

Hi Experts,

I am modifying a report to add some fields in the output (ALV).

The final internal table ITAB is field using collect statement in a loop which has numeric and non-numeric fields.

Suppose there are 2 entries in my internal table

First entry:

RLDNR (c2) :Z4

RYEAR(N4):2010

OBJNR:000000000000002157O

BLART:BLANK (new field added)

Second entry

RLDNR (c2) :Z4

RYEAR(N4):2010

OBJNR:000000000000028453

BLART(C2):GA

Collect itab.

I was expecting that the above 2 rows should be added using collect statement but as i have added BLART it is appending the data in ITAB.

How can i avoid this ?