Is there a faster way to determine that if the data I have in my filemaker database the same as the same as the data I have in a particular spreadsheet or in MS Access database?"
What way are you doing it now? A better question might be why is the same data possibly in all 3 or multiple locations?
Where does the data entered start-MS Access, Excel or FM?
Are you importing it into FM or exporting it somewhere else?
After import/export, the data should probably removed, or marked in a way where the same process wont create duplicates.