Biztalk and File Masks Bug /Feature ?

Recently I was debugging a Biztalk solution with a friend of mine Rajesh ,and we noticed a curious Masking issue with BizTalk

Suppose you give a mask

*.XML

Which of these files are picked up ?

A) Orders.xml
B) Orders.XMLTEST
C) Orders.XML.BAK
D) Orders.TXT
E) ORDERS.XMLINFO
F) ORDERS.XML_BACKUP

I am sure your answer is only A , but in reality Biztalk picks up all files except C and D for a mask *.xml

So instead of looking for a file which starts with * and ending with .xml,It seems Biztalk picks up any file which has wild character starts and has .xml in the name not necessarily ending

But the contradiction to that is if there is one more DOT [.] Case C which is not picked up

So the way the mask gets applied is wild character then matches the last Dot and then matches charecters followwing the dot

Is this an intended behaviour or Bug ?