If you are opening the same workbook in Excel multiple times, you may be inadvertently creating duplicate copies of the file. This can lead to confusion and wasted time if you are not careful. To avoid this problem, follow these steps:
In the General Options dialog box, select the Check for duplicates when saving checkbox. This will cause Excel to prompt you if you are trying to save a file with a name that already exists.
If you have multiple workbooks open and try to save one with a name that is already in use, Excel will automatically append a number to the end of the filename (e.g. "MyWorkbook (2).xlsx"). You can change this behavior by deselecting the "Auto name new files" checkbox in the "General Options"