> previous master block is getting commit as well beside commit for the second block.
That is how Forms works. You cannot commit a single block. COMMIT (or commit_form) commits all pending changes in the Forms, not just one block.
>the master block is not getting committed again.
The first commit has saved the changes. If there are no new changes in the master block, there will be nothing to commit.
Sorry for the wrong statement mention. In fact my master block is getting committed again by create another record in the table when I press the save button.
I think I have solved my problem by putting one trigger in the master block of on-update as null. This will not created another record in master block when I saved my detail block.