As you appear to have discovered Brigid, it may elevate the amount of shared DNA beyond what is expected for the relationship, or in other words, the relationship could appear to be closer than it actually is.
It is quite common in small or remote rural communities, back when people didn't travel much and often married within the local community. I have numerous examples in my tree from my ancestors in Somerset, and to a slightly lesser degree, in Lincolnshire.
As my uncle wrote in a letter setting out his recollections of growing up in a small Somerset village in the 1920s, all of the children that he went to school with were related to him and one another in some way.
It has caused me several difficulties in attempting to use DNA matches to corroborate my research. Often, on the face of it, the relationship is straightforward and leads to the expected common ancestor, but a wider investigation of the matches' ancestry reveals intervening relationships to other families from whom I am also descended, making it impossible to be certain whether the match is wholly, partly, or not at all how it initially appears.
Access to numerous related individuals' DNA for comparison in a chromosome browser might make it possible to draw more precise conclusions, but trying to arrange that is akin to attempting a manned mission to Mars in a model T Ford!
On one hand, you may find matches to more distant ancestors than would normally be expected, but then assigning them correctly could be nigh on impossible due to several intervening instances of pedigree collapse.
