Certain iMessage address shows up as different contact

I ran into the craziest thing. My husband's iMessage account is linked to two different emails. When I send an iMessage to a secondary email (as in, the one that is not assigned as Caller ID on his phone or his tablet), once it sends, it shows up as being sent to a different friend in my contact book! But, he receives the message and she does not. However, sometimes, if I continue to type into that discussion, either he will get the message, or she will. (I haven't quite figured out the pattern there to make that one reproducible.)

Is any one experiencing this and/or does anyone have suggestions on why this may be happening? I have checked their contact info entries in my address book repeatedly, and the offending email address is not in the random friend's contact info.