Using OpenQuery throws the “Duplicate column names are not allowed in result sets obtained through OPENQUERY and OPENROWSET. The column name "id" is a duplicate.” error. 

This error occurs with every JOIN. The tests I made: 

• SELECT * FROM OPENQUERY (UGOOGLESHEETS], 'SELECT * FROM Food_FoodSales as a, aEmployee Sample Data_Data] as b WHERE a.Region=b.Region') 

• SELECT * FROM OPENQUERY (QGOOGLESHEETS], 'SELECT a.id, b.id FROM Food_FoodSales a LEFT OUTER JOIN REmployee Sample Data_Data] b ON a.Region=b.Region') 

• SELECT * FROM OPENQUERY (NGOOGLESHEETS], 'SELECT a.id, b.id FROM Food_FoodSales a INNER JOIN EEmployee Sample Data_Data] b ON a.Region=b.Region') 

To fix this issue, you can simply use the standard SQL statement 

SELECT *  

FROM �GOOGLESHEETS].GCData GoogleSheets Sys].lGoogleSheets].GFood_FoodSales] a,  

sGOOGLESHEETS].>CData GoogleSheets Sys].oGoogleSheets]..Employee Sample Data_Data] b  

WHERE ba].�Region]=Hb]. Region]