Hi Bob, yes it is possible ,I have seen it with little owls but only heard of it with barn owls ,I also believe their was a piece in one of the national papers about the very subject were it did happen .Is it possible for them to be sharing the same barn as a nest site
At the risk of being a spoilsport at the party; the Barn Owl is schedule 1 species, so if you decide to photograph near its nest you are opening yourself up to liability should you cause any disturbance (£5k and/or 6 months at HM's pleasure).