Help Voice Actions adding too many names

[Salamando]

When I use Voice Actions to send an SMS, some names cause more than one person to show up in the "To" box. Example: When I say "SMS Jenny" which is my wife's first name, my wife and my sister pop up in the "To:" box. They share the same last name but my sister's name is Caitlin. This happens on several other contacts that have the same last name. I tried says "SMS FirstName LastName" but it does the same thing. Any help?