Hello Anil,
Once you have saved the bol entities then all the attributes will be set to read only mode at genil level so , you can not change the value once you click on save.I think , to change the values after save you need to handle the editability explicitly.
You have said that some times you are getting one entry and some times two entries in lv_collection. Can you explain when it is having one entry and when two entries?
Regards,
Santosh