Other content is moving rather than artboard's content

Hello

i hope message finds everyone in high spirits, I am working on the Ai and making some designs on a single artboard, lets say I am working on Artboard 1 (1st artboard) , after I had done everything mistakenly artboard 2 copy ( 2nd artboard) overlayed on Artboard 1 (1st artboard) , so when I moving or try to delete 2nd artboard so the content's of the 1st one artboard is also moving or deleting,

i can't undo it for some reason, Please tell me the solution so I get deleted 2nd one artboard without deleting the content of 1st one artboard

Thanks,

Rafique