As you say Steve anything is possible.
The name Allan was quite common in the parish of Loudon and its neighbours at the time in question. Barbara was a common forename for women in Scotland, I am not convinced that this was the case at that time South of Haidrians Wall, indeed the name of one lady only yclept Barbara comes to mind at present and that was Barbara Villiers.
My Ulster friend assures me that Barbara is still a favourite name there with the descendants of the Scots who moved from this area in 1606 as part of the Montgomery Hamilton settlement, no doubt there would be Allans among those early settlers, many of whom later moved to the Americas.