Replaced Sent Attachments

[KKane]

This problem seems to have only started in the last month or two.
A) I open an Excel sheet named ABC.XLS located in \FolderNameJanuary and
then Send To Mail Recipient as attachment.
B) I open an Excel sheet named ABC.XLS located in \FolderNameFebruary and
then Send To Mail Recipient as attachment.
C) I open an Excel sheet named ABC.XLS located in \FolderNameMarch and then
Send To Mail Recipient as attachment.
D) When I view the Sent folder I see the 3 messages. When I open any one of
them, the attachment is the same file as C) above
E) I open an Excel sheet named ABC.XLS located in \FolderNameCurrent and
then Send To Mail Recipient as attachment.
F) When I view the Sent folder I see the 4 messages. When I open any one of
them, the attachment is the same file as E) above

Note that this only happens if the attached file name was the same ABC.XLS.
There is no limit to how back it will replace, even messages 3 months old
with an attached file ABC.XLS will display the most current version which I
sent. The recipient does not matter, only the attached file name.

Can I fix this? I have used the option in Security of Excel to disable
personal information on Save however this does not seem to have solved the
problem.