You don't say what spreadsheet you're using in linux so I'll assume LibreOffice Calc.
Are you, by any chance, using maximised windows? I have dual screens and it works fine for me as long as the windows aren't maximised. Unmax the window then drag its edges to where you want it, across screens.
Edit: You can also have two maximised spreadsheets, one on each window. Simply drag the title bar.