I am using biomaRt (2.38.0) to retrieve genome data from Ensembl. When using the web interface to do this, there is a check-box option to limit a query to unique results only. This eliminates redundancy in the output.

Is there any way to implement the 'unique results only' option using biomaRt (2.38.0)?

The getBM() function has the argument uniqueRows which toggles this behaviour. However the default value is TRUE so it should do this unless explicitly asked not to. Do you have an example query where it isn't working correctly?