From which number did I get this text? I received a text from a number. My contact list had that number saved as well as 3 other numbers in the same contact card. 

How do I get to know which number had sent the text, when it shows only the name?  (the “recent” thing, in Phone app does not seem to work.)

I worked around it by deleting each number from the contact card and seeing how the “sender” changed.

There ought to be an easy way for the same.
Go to their contact info and there should be a mark next to number which sent the most recent text.