Hello @AjayV, I think I understand a little more about the issue. If you are wanting to apply RLS based on something like company_id for your dashboard, then you will likely need to run the joins like you were previously or find an alternate way to join company_id on each dataset. That is the only way to guarantee users have appropriate permissions when viewing the dashboard.
In that case, we can definitely find a way to aggregate the data to manage duplicate rows. You are going to have to utilize LAC-W aggregations so you can retrieve distinct values, and sum the results within a group.
The best way to figure out a solution would be if you could create a version of your analysis, with anonymized data for anything that may be sensitive or company specific, in Quick Sight Arena and share a link to it in your next response. That way I can test some alternative ways to handle the calculations you are looking for.