Cant answer that with a positive answer but some others may come in and help you out.
Some plants are most prone to cross pollination, things like Lupin, Climbing nasturtium,
Fox Gloves etc all spring to mind, the insects and bee's do this for us but as for your Nasturtiums I cant say yes or no. It's only free seeds I suppose you are talking about so give it a go, there are some people who have made money from finding new plants so good luck. WeeNel.