Eric M Russell (2/10/2016)
Hugo,My script returns the duplicate listed below, but your's appears to return none.
MemNoYMDStart YMDEndYMDStart YMDEnd
417 2001-10-01 2001-09-30 2001-06-01 2001-09-30
True. And one might debate whether or not an interval that ends before it even starts is able to overlap with other intervals or not.
Either way, I already mentioned in my post that these negative-length intervals will probably cause weird results. They should be filtered out before even starting to look for overlapping intervals.