[FIX]Fixe the issue o2m record duplication.

Hello,

Fixed the issue of o2m record duplication.

Demo: Install Event module -> Open any which having atleast one registration -> Now create new o2m record and then before saving the record click on button of other record on o2m and then click Save button of parent record.
You will get duplicated records in o2m, the reason is that when one click button the behavior is that web first saves the whole record and hence that o2m record also but it does not bufferred dataset is not reset and hence there is a record in to_create list so when parent record Save is called it again saves data of to_create list.

Thanks.