Load collision in CLI when re-loading an item a directory

component=Test

item-repository=sqltest/select1    (where select1 contains directories s1,s2,s3)

I load the item in a local workspace successfully (using loadrules).  

    <itemLoadRule>

        <component name="Test" />

        <item repositoryPath="/sqltest/select1" />

        <sandboxRelativePath pathPrefix="/sql" />

    </itemLoadRule>

Directory "sql/select1" is created in my local workspace and contains  s1, s2, s3

I then want to reload "select1/s1" using this loadrule and the -f option, 

    <itemLoadRule>

        <component name="Test" />

        <item repositoryPath="/sqltest/select1/s1" />

        <sandboxRelativePath pathPrefix="/sql/select1" />

    </itemLoadRule>

but get the error

          /sql/select1

          Problem running 'load'.

         Load could not complete due to collisions. Choose a different destination for the load

I can reload "select1" with the -f option, but not the subdir "select1/s1"

The same error occurs in reverse -  load "select1/s1"  and then try to load the full "select1" directory

Why won't the -f option allow the overwrite?  Is there a way to do this using cli and loadrules?