I don't think tableau can recognize the multi locations at once.
The way I would do is :
1. Create a calculated field, such as
WHEN .... THEN ...
WHEN ... THEN...
2. Only use single state to plot
3. Place the calculation from step 1 in color
If you are required to plot each of the states in a cell onto the map then each will have to be on a distinct row.
So unfortunately the best way to go about this would be to restructure your data, If these are specific groups you can create groups to aggregate the data by within tableau once the data is restructured.