Some approaches to consider:
> You could create an extract from your first file as a 'baseline' then you could append (add) data to the extract for each new file - Add Data to Extracts
> You could use a UNION to combine your sheets - Analyzing Related Data Across Multiple Excel Tabs | Tableau Software
Aready used These Approaches . but somehow I'm not getting Right Count
You asked how to handle your situation in Tableau, those two approaches are possible answers.
If those approaches aren't working for you, that's an entirely different set of questions - Which approach are you using? What is the 'right' count? What is the current count?
If you'd like help troubleshooting that, you'll need to provide much more details.