Outlook 2013 Rename Word Attachment

Hello Everyone !

Hoping you are having a good day. I'm having a really weird case with 2 of my users which said that when they attach 3 or more word or excel document into an email and send it over, the recepient reports to receive the documents with tittles changed .

Example they send 3 attachment:

SenderReceipient

Doc1 with text "ABC"                              Doc2 with text "ABC"
Doc2 with text "DEF"                              Doc3 with text "DEF"
Doc3 with text "GHI"              Doc1 with text "GHI"

I do have On premises Exchnage Servers not office 365 involved.