Generate multiple summaries

I am using the run_summarization.py example to summarize a custom dataset.
The dataset uses Trainer().

I would like to generate multiple summaries for each source. I know this cound be done setting the num_return_sequences parameter in the generate() function, however it seems the Trainer does not accept this parameter.

Is there an easy way to obtain multiple output with the Trainer? Otherwise, what other options do I have?