Could you please check the table names for TGB-FAS-Work, TGB-FAS-Work-AP and TGB-FAS-Work-EM.
The table will be same for all the three classes unless you have manually changed them.
Since you have already optimized the property for TGB-FAS-Work, a column has already been created in this table. So when you are again trying to optimize the property for TGB-FAS-Work-AP or TGB-FAS-Work-EM, as the column already exist in this table it is throwing the error you have mentioned.
I think you can try one of the below options now to optimize it for AP or EM.
1. Create a Declare index and optimize the column using this declare index and in RD you can have a class join with this declare index and use this column instead (write an activity to populate the old work objects data).
2. Another option you have is delete this column from the table manually and then again optimize the property and this time for the implemented class(run the columnpopulation utility ) .
3. Another option is to create a column with some other name in the same table and then map this column with the property in external mapping tab of class definition (in this option you will have to write an activity to populate this new column with old work objects data).