Pack and Go(original drawing has been modifed)

Good day.

I have used the PACK & GO to copy the assembly & drawing (DRAWING A), saved it as DRAWING B, and modified it afterwards. However I have noticed that after all the modification I have done in the DRAWING B, the original drawing (DRAWING A) has also been modified as what I have done in Drawing B. Although the modified date of Drawing A is the same.

Could you please advise me why is this happened?

Thank you so much for the response

SolidworksGeneral