Footnote style in Chicago 16A (Endnot X5.0.1)


I am using Chicago 16A and I have noticed an anomaly with the footnote citation. When I have two separate personal letters from the same author but to two different recipients, the footnote treats it as a repeat from the first letter and places an Ibid in the footnote.  It seems that Endnote is confused. This also happens if I have two separate letters from the same author to the same recipient but on different days. Any information and/or pics would be appreciated.

Thanks for your time,