What does you mean "the cells are the same"? 5, 10, and 15 do not sound the same to me. It sounds like you are copying and pasting formulas, which can show different answers in different worksheets. Do you want to preserve formulas, or just values? You can Paste Values to preserve the resulting value.

It would help if you would attach the source file. Under the text box where you type your reply click the Go Advanced button. On the next screen scroll down and click on Manage Attachments, which will show a pop-up window to Select and Upload a file. Then close the window.