SelectedVariableNames must be a unique subset of VariableNames

Solution:

SpreadsheetDatastore properties describe the format of the files in a datastore object, and control how the data is read from the datastore. Except for the Files property, you can specify the value of SpreadsheetDatastore properties using name-value pair arguments when you create the datastore object. To view or modify a property after creating the object, use the dot notation:

ds = spreadsheetDatastore('airlinesmall_subset.xlsx');
ds.Sheets = [1 2];
ds.Range = 'A1:C6';


For more information,

https://www.mathworks.com/help/matlab/ref/matlab.io.datastore.spreadsheetdatastore.html